diff --git a/client/package.json b/client/package.json
index 2628b9a..bbe114c 100644
--- a/client/package.json
+++ b/client/package.json
@@ -4,10 +4,10 @@
   "version": "0.0.1",
   "license": "MPL-2.0",
   "scripts": {
-    "analyze": "cross-env NODE_ENV=development webpack --analyze",
+    "analyze": "webpack --mode=production --analyze",
     "prebuild": "rimraf ../dist",
-    "build": "cross-env NODE_ENV=development webpack",
-    "develop": "cross-env NODE_ENV=development webpack serve"
+    "build": "webpack --mode=production",
+    "develop": "webpack serve --mode=development"
   },
   "dependencies": {
     "buffer": "6.0.3",
@@ -44,7 +44,6 @@
     "@types/react-helmet": "6.1.4",
     "@types/react-router-dom": "5.3.2",
     "babel-loader": "8.2.3",
-    "cross-env": "7.0.3",
     "css-loader": "6.5.1",
     "html-webpack-plugin": "5.5.0",
     "mini-css-extract-plugin": "2.4.5",
diff --git a/client/webpack.config.js b/client/webpack.config.js
index 744c09b..5337d7d 100644
--- a/client/webpack.config.js
+++ b/client/webpack.config.js
@@ -20,7 +20,6 @@ const config = {
     },
     static: [PUBLIC_PATH, UPLOAD_PATH],
   },
-  devtool: 'inline-source-map',
   entry: {
     main: [
       'core-js',
@@ -31,7 +30,6 @@ const config = {
       path.resolve(SRC_PATH, './index.jsx'),
     ],
   },
-  mode: 'none',
   module: {
     rules: [
       {
@@ -64,7 +62,6 @@ const config = {
       BUILD_DATE: new Date().toISOString(),
       // Heroku では SOURCE_VERSION 環境変数から commit hash を参照できます
       COMMIT_HASH: process.env.SOURCE_VERSION || '',
-      NODE_ENV: 'development',
     }),
     new MiniCssExtractPlugin({
       filename: 'styles/[name].css',
diff --git a/yarn.lock b/yarn.lock
index a8af3e6..76e8f2c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2160,13 +2160,6 @@ cosmiconfig@^7.0.0, cosmiconfig@^7.0.1:
     path-type "^4.0.0"
     yaml "^1.10.0"
 
-cross-env@7.0.3:
-  version "7.0.3"
-  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-7.0.3.tgz#865264b29677dc015ba8418918965dd232fc54cf"
-  integrity sha512-+/HKd6EgcQCJGh2PSjZuUitQBQynKor4wrFbRg4DtAgS1aWO+gU52xpH7M9ScGgXSYmAVS9bIJ8EzuaGw0oNAw==
-  dependencies:
-    cross-spawn "^7.0.1"
-
 cross-spawn@^6.0.5:
   version "6.0.5"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-6.0.5.tgz#4a5ec7c64dfae22c3a14124dbacdee846d80cbc4"
@@ -2178,7 +2171,7 @@ cross-spawn@^6.0.5:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
-cross-spawn@^7.0.1, cross-spawn@^7.0.3:
+cross-spawn@^7.0.3:
   version "7.0.3"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.3.tgz#f73a85b9d5d41d045551c177e2882d4ac85728a6"
   integrity sha512-iRDPJKUPVEND7dHPO8rkbOnPpyDygcDFtWjpeWNCgy8WP2rXcxXL8TskReQl6OrB2G7+UJrags1q15Fudc7G6w==