diff --git a/cmd/gen.go b/cmd/gen.go
index b78f69f..90ebd29 100644
--- a/cmd/gen.go
+++ b/cmd/gen.go
@@ -14,6 +14,9 @@ import (
 
 var fileFlagKey = "file"
 var colNameKey = "col"
+var minDepthKey = "min-depth"
+var minLogDepthKey = "min--log-depth"
+var maxDepthKey = "max-depth"
 
 var genCmd = &cobra.Command{
 	Use:   "gen",
@@ -42,7 +45,7 @@ var genCmd = &cobra.Command{
 			words = append(words, record[colIndex])
 		}
 
-		iroha := lib.NewIroha(words)
+		iroha := lib.NewIroha(words, &lib.DepthOptions{})
 		iroha.PrintWordCountMap()
 		iroha.PrintWordByKatakanaMap()
 		rowIndicesList, err := iroha.Search()
@@ -112,4 +115,18 @@ func init() {
 	if err := viper.BindPFlag(colNameKey, genCmd.Flags().Lookup(colNameKey)); err != nil {
 		panic(err)
 	}
+	if err := registerIntToFlags(genCmd, minDepthKey, -1, "min depth"); err != nil {
+		panic(err)
+	}
+	if err := registerIntToFlags(genCmd, maxDepthKey, -1, "max depth"); err != nil {
+		panic(err)
+	}
+	if err := registerIntToFlags(genCmd, minLogDepthKey, 0, "min log depth"); err != nil {
+		panic(err)
+	}
+}
+
+func registerIntToFlags(cmd *cobra.Command, name string, value int, usage string) error {
+	cmd.Flags().Int(name, value, usage)
+	return viper.BindPFlag(name, cmd.Flags().Lookup(name))
 }
diff --git a/lib/iroha.go b/lib/iroha.go
index 8c31d27..ccb1b1a 100644
--- a/lib/iroha.go
+++ b/lib/iroha.go
@@ -7,21 +7,25 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-var logDepthThreshold = 1
-var minParallelDepth = 1
-var maxParallelDepth = 2
-
 type Iroha struct {
 	katakanaBitsMap KatakanaBitsMap
 	katakana        *Katakana
 	log             *Log
+	depths          *DepthOptions
+}
+
+type DepthOptions struct {
+	MaxLog      int
+	MinParallel int
+	MaxParallel int
 }
 
-func NewIroha(words []string) *Iroha {
+func NewIroha(words []string, options *DepthOptions) *Iroha {
 	km, _ := newKatakanaBitsMap()
 	return &Iroha{
 		katakanaBitsMap: km,
 		katakana:        NewKatakana(words),
+		depths:          options,
 	}
 }
 
@@ -35,7 +39,7 @@ func (i *Iroha) PrintWordByKatakanaMap() {
 
 func (i *Iroha) Search() (rowIndicesList [][]int, err error) {
 	katakanaBitsAndWordsList := i.katakana.ListSortedKatakanaBitsAndWords()
-	i.log = NewLog(katakanaBitsAndWordsList, logDepthThreshold, minParallelDepth)
+	i.log = NewLog(katakanaBitsAndWordsList, i.depths.MaxLog, i.depths.MinParallel)
 	wordsList, _, err := i.searchByBits(katakanaBitsAndWordsList, WordBits(0))
 	if err != nil {
 		return nil, err
@@ -100,7 +104,7 @@ func (i *Iroha) searchByBits(katakanaBitsAndWords []*KatakanaBitsAndWords, remai
 	depth := int(KatakanaLen) - len(katakanaBitsAndWords)
 	var irohaWordLists [][]*Word
 
-	goroutineMode := depth >= minParallelDepth && depth <= maxParallelDepth
+	goroutineMode := depth >= i.depths.MinParallel && depth <= i.depths.MaxParallel
 
 	if goroutineMode {
 		eg := errgroup.Group{}