diff --git a/app.go b/app.go
index fd65da4..8ae5176 100644
--- a/app.go
+++ b/app.go
@@ -2,37 +2,15 @@ package main
 
 import (
 	"context"
-	"encoding/json"
 	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
-	"sort"
 	"strings"
-	"time"
 
 	"github.com/wailsapp/wails/v2/pkg/runtime"
 )
 
-type Nikki_date_t struct {
-	Year  int
-	Month int
-	Day   int
-}
-
-type Nikki_t struct {
-	Fname   string
-	Date    Nikki_date_t
-	Content string
-}
-
-type Setting_t struct {
-	Nikki_dir    string
-	Fname_format string
-}
-
-var default_Setting_data = Setting_t{Nikki_dir: "", Fname_format: "YYYY年MM月DD日.txt"}
-
 // App struct
 type App struct {
 	ctx               context.Context
@@ -82,133 +60,6 @@ func (a *App) Get_dir_fnames(dir_name string) []string {
 	return fnames
 }
 
-func (a *App) Add_nikki_today() {
-	if a.Setting_data.Nikki_dir == "" {
-		return
-	}
-
-	timezone := time.FixedZone("Asia/Tokyo", 9*60*60)
-	time_now := time.Now().In(timezone)
-	f, err := os.OpenFile(
-		path.Join(
-			a.Setting_data.Nikki_dir,
-			time_now.Format(TimeFormat_conv(a.Setting_data.Fname_format)),
-		),
-		os.O_WRONLY|os.O_CREATE, 0666,
-	)
-	if err != nil {
-	}
-	f.Close()
-}
-
-func (a *App) Parse_nikki_file(fname string) Nikki_t {
-	content, err := ioutil.ReadFile(path.Join(a.Setting_data.Nikki_dir, fname))
-	if err != nil {
-		panic(err)
-	}
-
-	Fname_format_golang := TimeFormat_conv(a.Setting_data.Fname_format)
-
-	t, err := time.Parse(Fname_format_golang, fname)
-
-	return Nikki_t{
-		Fname: fname, Content: string(content),
-		Date: Nikki_date_t{
-			Year:  t.Year(),
-			Month: int(t.Month()),
-			Day:   t.Day(),
-		},
-	}
-}
-
-func (a *App) Write_nikki_file(v Nikki_t) {
-	var err error
-	var f *os.File
-	f, err = os.Create(path.Join(a.Setting_data.Nikki_dir, v.Fname))
-	for err != nil {
-		f, err = os.Create(path.Join(a.Setting_data.Nikki_dir, v.Fname))
-		time.Sleep(time.Millisecond * 200)
-	}
-	defer f.Close()
-
-	_, err = f.Write([]byte(v.Content))
-	if err != nil {
-		panic(err)
-	}
-}
-
-func (a *App) Set_nikki(v []Nikki_t) {
-	for i, e := range v {
-		if a.Nikki_data[i].Content != e.Content {
-			a.Nikki_data[i].Content = e.Content
-			a.Write_nikki_file(a.Nikki_data[i])
-		}
-	}
-
-}
-
-func (a *App) Load_nikki() {
-	var reslut []Nikki_t
-	for _, e := range a.Get_dir_fnames(a.Setting_data.Nikki_dir) {
-		reslut = append(reslut, a.Parse_nikki_file(e))
-	}
-
-	sort.SliceStable(reslut, func(i, j int) bool {
-		if reslut[i].Date.Year != reslut[j].Date.Year {
-			return reslut[i].Date.Year > reslut[j].Date.Year
-		}
-		if reslut[i].Date.Month != reslut[j].Date.Month {
-			return reslut[i].Date.Month > reslut[j].Date.Month
-		}
-		return reslut[i].Date.Day > reslut[j].Date.Day
-	})
-	a.Nikki_data = reslut
-}
-
-func (a *App) Get_nikki() []Nikki_t {
-
-	return a.Nikki_data
-}
-
-func (a *App) Load_setting() {
-
-	setting_text, err := ioutil.ReadFile(a.setting_json_path)
-	if err == nil {
-		if err := json.Unmarshal(setting_text, &a.Setting_data); err != nil {
-			a.Setting_data = default_Setting_data
-		}
-	} else {
-		a.Setting_data = default_Setting_data
-	}
-
-}
-
-func (a *App) Write_setting() {
-	setting_text, err := json.Marshal(a.Setting_data)
-	f, err := os.Create(a.setting_json_path)
-	for err != nil {
-		f, err = os.Create(a.setting_json_path)
-		time.Sleep(time.Millisecond * 200)
-	}
-	defer f.Close()
-
-	_, err = f.Write([]byte(setting_text))
-	if err != nil {
-		panic(err)
-	}
-}
-
-func (a *App) Get_setting() Setting_t {
-	return a.Setting_data
-}
-
-func (a *App) Set_setting(v Setting_t) {
-	if a.Setting_data != v {
-		a.Setting_data = v
-		a.Write_setting()
-	}
-}
-
 func (a *App) Select_Nikki_dir_Dialog() string {
 	path_data, err := runtime.OpenDirectoryDialog(a.ctx, runtime.OpenDialogOptions{
 		DefaultDirectory: "",
diff --git a/app_nikki.go b/app_nikki.go
new file mode 100644
index 0000000..07e33a5
--- /dev/null
+++ b/app_nikki.go
@@ -0,0 +1,109 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"sort"
+	"time"
+)
+
+type Nikki_date_t struct {
+	Year  int
+	Month int
+	Day   int
+}
+
+type Nikki_t struct {
+	Fname   string
+	Date    Nikki_date_t
+	Content string
+}
+
+func (a *App) Add_nikki_today() {
+	if a.Setting_data.Nikki_dir == "" {
+		return
+	}
+
+	timezone := time.FixedZone("Asia/Tokyo", 9*60*60)
+	time_now := time.Now().In(timezone)
+	f, err := os.OpenFile(
+		path.Join(
+			a.Setting_data.Nikki_dir,
+			time_now.Format(TimeFormat_conv(a.Setting_data.Fname_format)),
+		),
+		os.O_WRONLY|os.O_CREATE, 0666,
+	)
+	if err != nil {
+	}
+	f.Close()
+}
+
+func (a *App) Parse_nikki_file(fname string) Nikki_t {
+	content, err := ioutil.ReadFile(path.Join(a.Setting_data.Nikki_dir, fname))
+	if err != nil {
+		panic(err)
+	}
+
+	Fname_format_golang := TimeFormat_conv(a.Setting_data.Fname_format)
+
+	t, err := time.Parse(Fname_format_golang, fname)
+
+	return Nikki_t{
+		Fname: fname, Content: string(content),
+		Date: Nikki_date_t{
+			Year:  t.Year(),
+			Month: int(t.Month()),
+			Day:   t.Day(),
+		},
+	}
+}
+
+func (a *App) Write_nikki_file(v Nikki_t) {
+	var err error
+	var f *os.File
+	f, err = os.Create(path.Join(a.Setting_data.Nikki_dir, v.Fname))
+	for err != nil {
+		f, err = os.Create(path.Join(a.Setting_data.Nikki_dir, v.Fname))
+		time.Sleep(time.Millisecond * 200)
+	}
+	defer f.Close()
+
+	_, err = f.Write([]byte(v.Content))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (a *App) Set_nikki(v []Nikki_t) {
+	for i, e := range v {
+		if a.Nikki_data[i].Content != e.Content {
+			a.Nikki_data[i].Content = e.Content
+			a.Write_nikki_file(a.Nikki_data[i])
+		}
+	}
+
+}
+
+func (a *App) Load_nikki() {
+	var reslut []Nikki_t
+	for _, e := range a.Get_dir_fnames(a.Setting_data.Nikki_dir) {
+		reslut = append(reslut, a.Parse_nikki_file(e))
+	}
+
+	sort.SliceStable(reslut, func(i, j int) bool {
+		if reslut[i].Date.Year != reslut[j].Date.Year {
+			return reslut[i].Date.Year > reslut[j].Date.Year
+		}
+		if reslut[i].Date.Month != reslut[j].Date.Month {
+			return reslut[i].Date.Month > reslut[j].Date.Month
+		}
+		return reslut[i].Date.Day > reslut[j].Date.Day
+	})
+	a.Nikki_data = reslut
+}
+
+func (a *App) Get_nikki() []Nikki_t {
+
+	return a.Nikki_data
+}
diff --git a/app_nikki_test.go b/app_nikki_test.go
new file mode 100644
index 0000000..65741e7
--- /dev/null
+++ b/app_nikki_test.go
@@ -0,0 +1,17 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParse_nikki_file(t *testing.T) {
+	app := App{}
+	app.Setting_data.Nikki_dir = "test-dir"
+	app.Setting_data.Fname_format = "YYYY年MM月DD日.txt"
+
+	assert.EqualExportedValues(t,
+		Nikki_t{Fname: "2024年09月19日.txt", Date: Nikki_date_t{Year: 2024, Month: 9, Day: 19}, Content: "Test!"},
+		app.Parse_nikki_file("2024年09月19日.txt"))
+}
diff --git a/app_setting.go b/app_setting.go
new file mode 100644
index 0000000..320a133
--- /dev/null
+++ b/app_setting.go
@@ -0,0 +1,54 @@
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"time"
+)
+
+type Setting_t struct {
+	Nikki_dir    string
+	Fname_format string
+}
+
+var default_Setting_data = Setting_t{Nikki_dir: "", Fname_format: "YYYY年MM月DD日.txt"}
+
+func (a *App) Get_setting() Setting_t {
+	return a.Setting_data
+}
+
+func (a *App) Set_setting(v Setting_t) {
+	if a.Setting_data != v {
+		a.Setting_data = v
+		a.Write_setting()
+	}
+}
+
+func (a *App) Write_setting() {
+	setting_text, err := json.Marshal(a.Setting_data)
+	f, err := os.Create(a.setting_json_path)
+	for err != nil {
+		f, err = os.Create(a.setting_json_path)
+		time.Sleep(time.Millisecond * 200)
+	}
+	defer f.Close()
+
+	_, err = f.Write([]byte(setting_text))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (a *App) Load_setting() {
+
+	setting_text, err := ioutil.ReadFile(a.setting_json_path)
+	if err == nil {
+		if err := json.Unmarshal(setting_text, &a.Setting_data); err != nil {
+			a.Setting_data = default_Setting_data
+		}
+	} else {
+		a.Setting_data = default_Setting_data
+	}
+
+}
diff --git a/app_test.go b/app_test.go
index c56d4e2..899dc31 100644
--- a/app_test.go
+++ b/app_test.go
@@ -27,13 +27,3 @@ func TestTimeFormat_conv(t *testing.T) {
 
 	assert.Equal(t, "2006年01月02日.txt", TimeFormat_conv("YYYY年MM月DD日.txt"))
 }
-
-func TestParse_nikki_file(t *testing.T) {
-	app := App{}
-	app.Setting_data.Nikki_dir = "test-dir"
-	app.Setting_data.Fname_format = "YYYY年MM月DD日.txt"
-
-	assert.EqualExportedValues(t,
-		Nikki_t{Fname: "2024年09月19日.txt", Date: Nikki_date_t{Year: 2024, Month: 9, Day: 19}, Content: "Test!"},
-		app.Parse_nikki_file("2024年09月19日.txt"))
-}