diff --git a/src/ui/flutter_app/lib/main.dart b/src/ui/flutter_app/lib/main.dart
index c47d817e..4a9a8022 100644
--- a/src/ui/flutter_app/lib/main.dart
+++ b/src/ui/flutter_app/lib/main.dart
@@ -154,7 +154,8 @@ class _SanmillAppState extends State<SanmillApp> {
         GlobalCupertinoLocalizations.delegate,
       ],
       supportedLocales: supportedLocales,
-      theme: ThemeData(primarySwatch: AppTheme.appPrimaryColor),
+      theme: AppTheme.lightThemeData,
+      darkTheme: AppTheme.darkThemeData,
       debugShowCheckedModeBanner: false,
       home: Scaffold(
         body: DoubleBackToCloseApp(
diff --git a/src/ui/flutter_app/lib/style/app_theme.dart b/src/ui/flutter_app/lib/style/app_theme.dart
index 86853111..ff019223 100644
--- a/src/ui/flutter_app/lib/style/app_theme.dart
+++ b/src/ui/flutter_app/lib/style/app_theme.dart
@@ -6,8 +6,18 @@ import 'package:sanmill/style/colors.dart';
 class AppTheme {
   AppTheme._();
 
-  // Color
+  // Theme data
+  static var lightThemeData = ThemeData(
+    primarySwatch: AppTheme.appPrimaryColor,
+    brightness: Brightness.light,
+  );
 
+  static var darkThemeData = ThemeData(
+    primarySwatch: AppTheme.appPrimaryColor,
+    brightness: Brightness.dark,
+  );
+
+  // Color
   static var appPrimaryColor = Colors.green; // Appbar & Dialog button
   static var dialogTitleColor = appPrimaryColor;