diff --git a/gradlew b/gradlew
old mode 100644
new mode 100755
diff --git a/src/main/java/baseball/App.java b/src/main/java/baseball/App.java
new file mode 100644
index 0000000..a392cc1
--- /dev/null
+++ b/src/main/java/baseball/App.java
@@ -0,0 +1,17 @@
+package baseball;
+
+import baseball.controller.GameController;
+import baseball.game.Game;
+
+import java.util.Scanner;
+
+public class App {
+    public static void main(String[] args) {
+        Game game = new Game();
+        Scanner scanner = new Scanner(System.in);
+
+        GameController gameController = new GameController(game, scanner);
+
+        gameController.run();
+    }
+}
diff --git a/src/main/java/baseball/checker/BallChecker.java b/src/main/java/baseball/checker/BallChecker.java
new file mode 100644
index 0000000..d5deace
--- /dev/null
+++ b/src/main/java/baseball/checker/BallChecker.java
@@ -0,0 +1,32 @@
+package baseball.checker;
+
+import baseball.matcher.NumberMatcher;
+import baseball.matcher.PositionMatcher;
+import baseball.config.Constants;
+import java.util.List;
+
+public class BallChecker {
+    private final NumberMatcher numberMatcher;
+    private final PositionMatcher positionMatcher;
+
+    public BallChecker() {
+        this.numberMatcher = new NumberMatcher();
+        this.positionMatcher = new PositionMatcher();
+    }
+
+    public int countBalls(List<Integer> guess, List<Integer> answer) {
+        int ballCount = Constants.ZERO;
+        for (int i = 0; i < Constants.NUMBER_COUNT; i++) {
+            if (isBall(guess.get(i), answer, i)) {
+                ballCount++;
+            }
+        }
+        return ballCount;
+    }
+
+    private boolean isBall(int guessedNumber, List<Integer> answer, int index) {
+        // 볼 조건: 위치가 맞지 않고 숫자가 정답에 포함된 경우
+        return !positionMatcher.isPositionMatching(answer, guessedNumber, index)
+                && answer.contains(guessedNumber);
+    }
+}
diff --git a/src/main/java/baseball/checker/StrikeChecker.java b/src/main/java/baseball/checker/StrikeChecker.java
new file mode 100644
index 0000000..fc6ccc6
--- /dev/null
+++ b/src/main/java/baseball/checker/StrikeChecker.java
@@ -0,0 +1,32 @@
+package baseball.checker;
+
+import baseball.matcher.NumberMatcher;
+import baseball.matcher.PositionMatcher;
+import baseball.config.Constants;
+import java.util.List;
+
+// 스트라이크 개수 계산
+public class StrikeChecker {
+    private final NumberMatcher numberMatcher;
+    private final PositionMatcher positionMatcher;
+
+    public StrikeChecker() {
+        this.numberMatcher = new NumberMatcher();
+        this.positionMatcher = new PositionMatcher();
+    }
+
+    public int countStrikes(List<Integer> guess, List<Integer> answer) {
+        int strikeCount = Constants.ZERO;
+        for (int i = 0; i < Constants.NUMBER_COUNT; i++) {
+            if (isStrike(guess.get(i), answer, i)) {
+                strikeCount++;
+            }
+        }
+        return strikeCount;
+    }
+
+    private boolean isStrike(int guessedNumber, List<Integer> answer, int index) {
+        return numberMatcher.isMatching(guessedNumber, answer.get(index))
+                && positionMatcher.isPositionMatching(answer, guessedNumber, index);
+    }
+}
diff --git a/src/main/java/baseball/config/Constants.java b/src/main/java/baseball/config/Constants.java
new file mode 100644
index 0000000..1b972b5
--- /dev/null
+++ b/src/main/java/baseball/config/Constants.java
@@ -0,0 +1,9 @@
+package baseball.config;
+
+public class Constants {
+    public static final int NUMBER_COUNT = 3; // 숫자 개수
+    public static final int MIN_NUMBER = 1;   // 최소 숫자
+    public static final int MAX_NUMBER = 9;   // 최대 숫자
+    public static final int ZERO = 0;
+    public static final int WINNING_STRIKES = 3;
+}
diff --git a/src/main/java/baseball/controller/GameController.java b/src/main/java/baseball/controller/GameController.java
new file mode 100644
index 0000000..36f4306
--- /dev/null
+++ b/src/main/java/baseball/controller/GameController.java
@@ -0,0 +1,32 @@
+package baseball.controller;
+
+import baseball.game.Game;
+import baseball.io.Message;
+
+import java.util.Scanner;
+
+public class GameController {
+    private final Game game;
+    private final Scanner scanner;
+
+    // 의존성 주입: 외부에서 객체를 주입받도록 생성자 수정
+    public GameController(Game game, Scanner scanner) {
+        this.game = game;
+        this.scanner = scanner;
+    }
+
+    public void run() {
+        boolean isRunning = true;
+        while (isRunning) {
+            game.start();
+            isRunning = promptRestart();
+        }
+        Message.printMessage(Message.GAME_END);
+    }
+
+    private boolean promptRestart() {
+        Message.printMessage(Message.RESTART_PROMPT);
+        String choice = scanner.nextLine().trim();
+        return choice.equals("1");
+    }
+}
diff --git a/src/main/java/baseball/game/Game.java b/src/main/java/baseball/game/Game.java
new file mode 100644
index 0000000..ccc0974
--- /dev/null
+++ b/src/main/java/baseball/game/Game.java
@@ -0,0 +1,60 @@
+package baseball.game;
+
+import baseball.validation.Validator;
+import baseball.io.InputView;
+import baseball.io.ResultView;
+import baseball.model.Result;
+
+import java.util.List;
+
+public class Game {
+    private List<Integer> answer;
+    private Validator validator;
+    private RandomNumberGenerator randomNumberGenerator;
+    private GuessChecker guessChecker;
+
+    public Game() {
+        this.randomNumberGenerator = new RandomNumberGenerator();
+        this.answer = randomNumberGenerator.generate();
+        this.validator = new Validator();
+        this.guessChecker = new GuessChecker(answer);
+    }
+
+    public Game(List<Integer> answer) {
+        this.answer = answer;
+        this.validator = new Validator();
+        this.guessChecker = new GuessChecker(answer);
+    }
+
+    // 주석으로 바꾸면 RED
+    public List<Integer> getAnswer() {
+        return answer;
+    }
+    // 주석으로 바꾸면 RED
+    public Result checkGuess(List<Integer> guess) {
+        validator.validate(guess);  // 유효성 검사
+        return guessChecker.check(guess);  // 스트라이크와 볼 계산 후 Result 반환
+    }
+
+    public void start() {
+        boolean isCorrect = false;
+        while (!isCorrect) {
+            try {
+                List<Integer> guess = InputView.getUserInput();
+                validator.validate(guess);
+
+                // GuessChecker로부터 얻는 결과를 StrikeAndBall로 변경
+                Result strikeAndBall = guessChecker.check(guess);
+
+                // StrikeAndBall 객체를 ResultView로 전달
+                ResultView.printResult(strikeAndBall);
+
+                // 스트라이크가 3개일 때 isCorrect를 true로 설정
+                isCorrect = strikeAndBall.getStrike() == 3;
+            } catch (IllegalArgumentException e) {
+                System.out.println("입력 오류: " + e.getMessage());
+            }
+        }
+        System.out.println("3개의 숫자를 모두 맞히셨습니다! 게임 종료");
+    }
+}
diff --git a/src/main/java/baseball/game/GuessChecker.java b/src/main/java/baseball/game/GuessChecker.java
new file mode 100644
index 0000000..9520a14
--- /dev/null
+++ b/src/main/java/baseball/game/GuessChecker.java
@@ -0,0 +1,26 @@
+package baseball.game;
+
+import baseball.checker.BallChecker;
+import baseball.checker.StrikeChecker;
+import baseball.model.Result;
+import baseball.model.Result;
+
+import java.util.List;
+
+class GuessChecker {
+    private List<Integer> answer;
+    private StrikeChecker strikeChecker;
+    private BallChecker ballChecker;
+
+    public GuessChecker(List<Integer> answer) {
+        this.answer = answer;
+        this.strikeChecker = new StrikeChecker();
+        this.ballChecker = new BallChecker();
+    }
+
+    public Result check(List<Integer> guess) {
+        int strike = strikeChecker.countStrikes(guess, answer);
+        int ball = ballChecker.countBalls(guess, answer);
+        return new Result(strike, ball);
+    }
+}
diff --git a/src/main/java/baseball/game/RandomNumberGenerator.java b/src/main/java/baseball/game/RandomNumberGenerator.java
new file mode 100644
index 0000000..368aeda
--- /dev/null
+++ b/src/main/java/baseball/game/RandomNumberGenerator.java
@@ -0,0 +1,22 @@
+package baseball.game;
+
+import baseball.config.Constants;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+public class RandomNumberGenerator {
+
+    public List<Integer> generate() {
+        List<Integer> numbers = new ArrayList<>();
+        Random random = new Random();
+        while (numbers.size() < Constants.NUMBER_COUNT) {
+            int num = random.nextInt(Constants.MAX_NUMBER) + Constants.MIN_NUMBER;
+            if (!numbers.contains(num)) {
+                numbers.add(num);
+            }
+        }
+        return numbers;
+    }
+}
diff --git a/src/main/java/baseball/io/InputView.java b/src/main/java/baseball/io/InputView.java
new file mode 100644
index 0000000..d148229
--- /dev/null
+++ b/src/main/java/baseball/io/InputView.java
@@ -0,0 +1,67 @@
+package baseball.io;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class InputView {
+
+    private static final Scanner scanner = new Scanner(System.in);
+
+    public static List<Integer> getUserInput() {
+        while (true) {
+            try {
+                String input = getInputFromUser();
+                validateRawInput(input);
+                List<Integer> numbers = extractNumbers(input);
+                validateNumbers(numbers);
+                return numbers;
+            } catch (IllegalArgumentException e) {
+                System.out.println("ERROR : " + e.getMessage());
+            }
+        }
+    }
+
+    private static String getInputFromUser() {
+        System.out.print("숫자를 입력해 주세요(1에서 9 사이의 숫자 3개): ");
+        return scanner.nextLine().trim();
+    }
+
+    static void validateRawInput(String input) {
+        if (input.isEmpty()) {
+            throw new IllegalArgumentException("입력값이 비어있습니다. 숫자 3개를 입력하세요.");
+        }
+        if (input.length() != 3) {
+            throw new IllegalArgumentException("입력값은 정확히 3자리여야 합니다.");
+        }
+        if (!input.matches("[1-9]+")) {  // 숫자가 아닌 문자나 특수기호를 처리
+            throw new IllegalArgumentException("입력값에는 1에서 9 사이의 숫자만 포함되어야 합니다.");
+        }
+    }
+
+    static List<Integer> extractNumbers(String input) {
+        List<Integer> numbers = new ArrayList<>();
+
+        // 입력에서 숫자만 추출하고 공백은 무시
+        for (char c : input.toCharArray()) {
+            if (Character.isDigit(c)) {
+                int num = Character.getNumericValue(c);
+                numbers.add(num);
+            }
+        }
+
+        return numbers;
+    }
+
+    static void validateNumbers(List<Integer> numbers) {
+        if (numbers.size() != 3) {
+            throw new IllegalArgumentException("숫자 3개를 정확히 입력해야 합니다.");
+        }
+        if (numbers.stream().distinct().count() != 3) {
+            throw new IllegalArgumentException("각 숫자는 중복되지 않아야 합니다.");
+        }
+        if (!numbers.stream().allMatch(n -> n >= 1 && n <= 9)) {
+            throw new IllegalArgumentException("모든 숫자는 1에서 9 사이여야 합니다.");
+        }
+    }
+}
diff --git a/src/main/java/baseball/io/Message.java b/src/main/java/baseball/io/Message.java
new file mode 100644
index 0000000..bd90579
--- /dev/null
+++ b/src/main/java/baseball/io/Message.java
@@ -0,0 +1,12 @@
+package baseball.io;
+
+public class Message {
+
+    public static final String RESTART_PROMPT = "게임을 새로 시작은 1, 종료 2를 입력하세요.";
+    public static final String GAME_END = "게임 종료";
+    public static final String GAME_COMPLETE = "3개의 숫자를 모두 맞히셨습니다! 게임 종료한다요~~~~~~~~~";
+
+    public static void printMessage(String message) {
+        System.out.println(message);
+    }
+}
diff --git a/src/main/java/baseball/io/ResultView.java b/src/main/java/baseball/io/ResultView.java
new file mode 100644
index 0000000..7a9d6a8
--- /dev/null
+++ b/src/main/java/baseball/io/ResultView.java
@@ -0,0 +1,13 @@
+package baseball.io;
+
+import baseball.model.Result;
+
+public class ResultView {
+    public static void printResult(Result strikeAndBall) {
+        if (strikeAndBall.getStrike() == 0 && strikeAndBall.getBall() == 0) {
+            System.out.println("낫싱");
+        } else {
+            System.out.println(strikeAndBall.getBall() + "볼 " + strikeAndBall.getStrike() + "스트라이크");
+        }
+    }
+}
diff --git a/src/main/java/baseball/matcher/NumberMatcher.java b/src/main/java/baseball/matcher/NumberMatcher.java
new file mode 100644
index 0000000..55bbe5d
--- /dev/null
+++ b/src/main/java/baseball/matcher/NumberMatcher.java
@@ -0,0 +1,15 @@
+package baseball.matcher;
+
+import java.util.List;
+
+// 숫자가 일치 하는지 비교 하고 싶은데....
+public class NumberMatcher {
+
+    public boolean isMatching(int guessedNumber, int answerNumber) {
+        return guessedNumber == answerNumber;
+    }
+    // 숫자가 정답 리스트에 포함되어 있는지 확인하는 메서드
+    public boolean isNumberMatching(List<Integer> answer, int guessedNumber) {
+        return answer.contains(guessedNumber);
+    }
+}
diff --git a/src/main/java/baseball/matcher/PositionMatcher.java b/src/main/java/baseball/matcher/PositionMatcher.java
new file mode 100644
index 0000000..3c175e8
--- /dev/null
+++ b/src/main/java/baseball/matcher/PositionMatcher.java
@@ -0,0 +1,11 @@
+package baseball.matcher;
+
+import java.util.List;
+
+//숫자가 위치가 일치 하는지 비교
+public class PositionMatcher {
+
+    public boolean isPositionMatching(List<Integer> answer, int guessedNumber, int index) {
+        return answer.get(index) == guessedNumber;
+    }
+}
diff --git a/src/main/java/baseball/model/Result.java b/src/main/java/baseball/model/Result.java
new file mode 100644
index 0000000..e414c60
--- /dev/null
+++ b/src/main/java/baseball/model/Result.java
@@ -0,0 +1,36 @@
+package baseball.model;
+
+import baseball.config.Constants;
+import baseball.validation.Validator;
+
+public class Result {
+    private final int strike;
+    private final int ball;
+
+    // 생성자
+    public Result(int strike, int ball) {
+        Validator.validateStrikeAndBall(strike, ball); // 유효성 검증
+        this.strike = strike;
+        this.ball = ball;
+    }
+
+    // 스트라이크 개수 반환
+    public int getStrike() {
+        return strike;
+    }
+
+    // 볼 개수 반환
+    public int getBall() {
+        return ball;
+    }
+
+    // 정답 여부 확인
+    public boolean isCorrect() {
+        return strike == Constants.WINNING_STRIKES; // 상수로 대체
+    }
+
+    @Override
+    public String toString() {
+        return String.format("결과: %d 스트라이크, %d 볼!", strike, ball);
+    }
+}
diff --git a/src/main/java/baseball/validation/Validator.java b/src/main/java/baseball/validation/Validator.java
new file mode 100644
index 0000000..2c018c1
--- /dev/null
+++ b/src/main/java/baseball/validation/Validator.java
@@ -0,0 +1,38 @@
+package baseball.validation;
+
+import baseball.config.Constants;
+
+import java.util.List;
+
+public class Validator {
+
+    public void validate(List<Integer> guess) {
+        validateSize(guess);
+        validateDuplicates(guess);
+        validateRange(guess);
+    }
+
+    private void validateSize(List<Integer> guess) {
+        if (guess.size() != Constants.NUMBER_COUNT) {
+            throw new IllegalArgumentException("숫자 " + Constants.NUMBER_COUNT + "개를 정확히 입력해야 합니다.");
+        }
+    }
+
+    private void validateDuplicates(List<Integer> guess) {
+        if (guess.stream().distinct().count() != Constants.NUMBER_COUNT) {
+            throw new IllegalArgumentException("각 숫자는 중복되지 않아야 합니다.");
+        }
+    }
+
+    private void validateRange(List<Integer> guess) {
+        if (!guess.stream().allMatch(n -> n >= Constants.MIN_NUMBER && n <= Constants.MAX_NUMBER)) {
+            throw new IllegalArgumentException("모든 숫자는 " + Constants.MIN_NUMBER + "에서 " + Constants.MAX_NUMBER + " 사이여야 합니다.");
+        }
+    }
+
+    public static void validateStrikeAndBall(int strike, int ball) {
+        if (strike < 0 || ball < 0) {
+            throw new IllegalArgumentException("스트라이크랑 볼 개수는 음수일 수 없음!");
+        }
+    }
+}
diff --git a/src/test/java/baseball/AppTest.java b/src/test/java/baseball/AppTest.java
new file mode 100644
index 0000000..1d95e8a
--- /dev/null
+++ b/src/test/java/baseball/AppTest.java
@@ -0,0 +1,4 @@
+package baseball;
+
+public class AppTest {
+}
diff --git a/src/test/java/baseball/checker/BallCheckerTest.java b/src/test/java/baseball/checker/BallCheckerTest.java
new file mode 100644
index 0000000..11ac304
--- /dev/null
+++ b/src/test/java/baseball/checker/BallCheckerTest.java
@@ -0,0 +1,56 @@
+package baseball.checker;
+
+import baseball.config.Constants;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BallCheckerTest {
+
+    private BallChecker ballChecker;
+    private List<Integer> answer;
+
+    @BeforeEach
+    @DisplayName("BallChecker랑 정답 리스트 초기화함")
+    public void setUp() {
+        ballChecker = new BallChecker();
+        answer = Arrays.asList(1,2,3);
+    }
+
+    @Test
+    @DisplayName("볼 없음: 예상한 숫자가 정답에 없을 때")
+    public void testNoBalls() {
+        List<Integer> guess = Arrays.asList(4, 5, 6);
+        int balls = ballChecker.countBalls(guess, answer);
+        assertEquals(Constants.ZERO, balls, "볼 없어야 됨.");
+    }
+
+    @Test
+    @DisplayName("1개의 볼 있음: 1이 정답에 있지만 위치가 다를 때")
+    public void testOneBall() {
+        List<Integer> guess = Arrays.asList(4, 1, 6);
+        int balls = ballChecker.countBalls(guess, answer);
+        assertEquals(1, balls, "1개의 볼이어야 됨.");
+    }
+
+    @Test
+    @DisplayName("2개의 볼 있음: 1이랑 3이 정답에 있지만 위치가 다를 때")
+    public void testTwoBalls() {
+        List<Integer> guess = Arrays.asList(3, 2, 1);
+        int balls = ballChecker.countBalls(guess, answer);
+        assertEquals(2, balls, "2개의 볼이어야 됨.");
+    }
+
+    @Test
+    @DisplayName("3개의 볼 있음: 숫자 다 맞지만 위치 다를 때")
+    public void testAllBalls() {
+        List<Integer> guess = Arrays.asList(3, 1, 2);
+        int balls = ballChecker.countBalls(guess, answer);
+        assertEquals(3, balls, "3개의 볼이어야 됨.");
+    }
+}
diff --git a/src/test/java/baseball/checker/StrikeCheckerTest.java b/src/test/java/baseball/checker/StrikeCheckerTest.java
new file mode 100644
index 0000000..17e0c98
--- /dev/null
+++ b/src/test/java/baseball/checker/StrikeCheckerTest.java
@@ -0,0 +1,56 @@
+package baseball.checker;
+
+import baseball.config.Constants;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class StrikeCheckerTest {
+
+    private StrikeChecker strikeChecker;
+    private List<Integer> answer;
+
+    @BeforeEach
+    @DisplayName("StrikeChecker랑 정답 리스트 초기화함")
+    public void setUp() {
+        strikeChecker = new StrikeChecker();
+        answer = Arrays.asList(1, 2, 3);
+    }
+
+    @Test
+    @DisplayName("스트라이크 없음: 예상한 숫자가 정답이랑 안 맞을 때")
+    public void testNoStrikes() {
+        List<Integer> guess = Arrays.asList(4, 5, 6);
+        int strikes = strikeChecker.countStrikes(guess, answer);
+        assertEquals(Constants.ZERO, strikes, "스트라이크 없음.");
+    }
+
+    @Test
+    @DisplayName("1개 스트라이크: 하나 맞고 위치도 맞을 때")
+    public void testOneStrike() {
+        List<Integer> guess = Arrays.asList(1, 5, 6);
+        int strikes = strikeChecker.countStrikes(guess, answer);
+        assertEquals(1, strikes, "1개의 스트라이크임.");
+    }
+
+    @Test
+    @DisplayName("2개 스트라이크: 두 개 맞고 위치도 맞을 때")
+    public void testTwoStrikes() {
+        List<Integer> guess = Arrays.asList(1, 2, 6);
+        int strikes = strikeChecker.countStrikes(guess, answer);
+        assertEquals(2, strikes, "2개의 스트라이크임.");
+    }
+
+    @Test
+    @DisplayName("3개 스트라이크: 전부 다 맞을 때")
+    public void testThreeStrikes() {
+        List<Integer> guess = Arrays.asList(1, 2, 3);
+        int strikes = strikeChecker.countStrikes(guess, answer);
+        assertEquals(3, strikes, "3개의 스트라이크임.");
+    }
+}
diff --git a/src/test/java/baseball/game/GameTest.java b/src/test/java/baseball/game/GameTest.java
new file mode 100644
index 0000000..70143de
--- /dev/null
+++ b/src/test/java/baseball/game/GameTest.java
@@ -0,0 +1,36 @@
+package baseball.game;
+
+import baseball.model.Result;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.DisplayName;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class GameTest {
+
+    @Test
+    @DisplayName("랜덤 숫자 잘 생성됐는지 확인해보자")
+    public void testGenerateRandomNumbers() {
+        Game game = new Game();
+        List<Integer> numbers = game.getAnswer();
+
+        assertEquals(3, numbers.size(), "숫자 딱 3개 나와야 함.");
+        assertTrue(numbers.stream().allMatch(n -> n >= 1 && n <= 9),
+                "1에서 9 사이 숫자만 있어야 함.");
+        assertEquals(3, numbers.stream().distinct().count(),
+                "중복된 숫자 있으면 안 됨.");
+    }
+
+    @Test
+    @DisplayName("정답 맞췄을 때 3 스트라이크인지 체크하자")
+    public void testCheckGuessCorrect() {
+        Game game = new Game(List.of(4, 2, 5));
+        Result result = game.checkGuess(List.of(4, 2, 5));
+
+        assertEquals(3, result.getStrike(), "3 스트라이크 나왔음.");
+        assertEquals(0, result.getBall(), "볼 하나도 없음.");
+        assertTrue(result.isCorrect(), "정답 맞췄으니까 게임 끝났음.");
+    }
+}
diff --git a/src/test/java/baseball/game/GuessCheckerTest.java b/src/test/java/baseball/game/GuessCheckerTest.java
new file mode 100644
index 0000000..bc78072
--- /dev/null
+++ b/src/test/java/baseball/game/GuessCheckerTest.java
@@ -0,0 +1,50 @@
+package baseball.game;
+
+import baseball.model.Result;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class GuessCheckerTest {
+
+    private GuessChecker guessChecker;
+    private List<Integer> answer;
+
+    @BeforeEach
+    public void setUp() {
+        answer = Arrays.asList(1, 2, 3);
+        guessChecker = new GuessChecker(answer);
+    }
+
+    @Test
+    @DisplayName("0 스트라이크, 0 볼 나오는지 확인해보셈")
+    public void testNoStrikeNoBall() {
+        List<Integer> guess = Arrays.asList(4, 5, 6);
+        Result result = guessChecker.check(guess);
+        assertEquals(0, result.getStrike(), "스트라이크는 0이어야 함");
+        assertEquals(0, result.getBall(), "볼은 0이어야 함");
+    }
+
+    @Test
+    @DisplayName("1 스트라이크, 1 볼 나오는지 확인해보셈")
+    public void testOneStrikeOneBall() {
+        List<Integer> guess = Arrays.asList(1, 3, 4);
+        Result result = guessChecker.check(guess);
+        assertEquals(1, result.getStrike(), "스트라이크는 1이어야 함");
+        assertEquals(1, result.getBall(), "볼은 1이어야 함");
+    }
+
+    @Test
+    @DisplayName("3 스트라이크 나오는지 확인해보셈")
+    public void testThreeStrikes() {
+        List<Integer> guess = Arrays.asList(1, 2, 3);
+        Result result = guessChecker.check(guess);
+        assertEquals(3, result.getStrike(), "스트라이크는 3이어야 함");
+        assertEquals(0, result.getBall(), "볼은 0이어야 함");
+    }
+}
diff --git a/src/test/java/baseball/game/RandomNumberGeneratorTest.java b/src/test/java/baseball/game/RandomNumberGeneratorTest.java
new file mode 100644
index 0000000..2fe0972
--- /dev/null
+++ b/src/test/java/baseball/game/RandomNumberGeneratorTest.java
@@ -0,0 +1,47 @@
+package baseball.game;
+
+import baseball.config.Constants;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class RandomNumberGeneratorTest {
+
+    private RandomNumberGenerator randomNumberGenerator;
+
+    @BeforeEach
+    public void setUp() {
+        randomNumberGenerator = new RandomNumberGenerator();
+    }
+
+    @Test
+    @DisplayName("생성된 숫자 개수 맞는지 확인해보셈")
+    public void testGenerateNumberCount() {
+        List<Integer> numbers = randomNumberGenerator.generate();
+        assertEquals(Constants.NUMBER_COUNT, numbers.size(), "생성된 숫자의 개수가 올바르지 않음");
+    }
+
+    @Test
+    @DisplayName("숫자 중복 안되는지 확인해보셈")
+    public void testNoDuplicateNumbers() {
+        List<Integer> numbers = randomNumberGenerator.generate();
+        Set<Integer> numberSet = new HashSet<>(numbers);
+        assertEquals(numbers.size(), numberSet.size(), "중복된 숫자가 있음");
+    }
+
+    @Test
+    @DisplayName("숫자 범위 맞는지 확인해보셈")
+    public void testNumberRange() {
+        List<Integer> numbers = randomNumberGenerator.generate();
+        for (int num : numbers) {
+            assertTrue(num >= Constants.MIN_NUMBER && num <= Constants.MAX_NUMBER,
+                    "숫자가 범위를 벗어남: " + num);
+        }
+    }
+}
diff --git a/src/test/java/study/StringTest.java b/src/test/java/study/StringTest.java
deleted file mode 100644
index 43e47d9..0000000
--- a/src/test/java/study/StringTest.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package study;
-
-import org.junit.jupiter.api.Test;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-public class StringTest {
-    @Test
-    void replace() {
-        String actual = "abc".replace("b", "d");
-        assertThat(actual).isEqualTo("adc");
-    }
-}