diff --git a/lib/screens/change_password_screen.dart b/lib/screens/change_password_screen.dart
index 9f060bf..b0d1b66 100644
--- a/lib/screens/change_password_screen.dart
+++ b/lib/screens/change_password_screen.dart
@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 import 'package:http/http.dart' as http;
 import '../config.dart';
 import '../theme/app_palette.dart';
+import '../ui/app_notice.dart';
 import '../ui/login_screen.dart';
 
 // 💡 main.dart 파일의 최하단(다른 클래스 중괄호 밖)에 붙여넣으세요.
@@ -22,9 +23,7 @@ class _ChangePasswordScreenState extends State<ChangePasswordScreen> {
   Future<void> _updatePassword() async {
     String newPw = _pwController.text.trim();
     if (newPw.isEmpty || newPw == "1234") {
-      ScaffoldMessenger.of(context).showSnackBar(
-        const SnackBar(content: Text('초기 비밀번호와 다른 안전한 비밀번호를 입력하세요.')),
-      );
+      AppNotice.show(context, '초기 비밀번호와 다른 안전한 비밀번호를 입력하세요.');
       return;
     }
 
@@ -38,9 +37,7 @@ class _ChangePasswordScreenState extends State<ChangePasswordScreen> {
 
       final res = jsonDecode(response.body);
       if (response.statusCode == 200 && res['status'] == 'success') {
-        ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(content: Text('비밀번호 변경 완료! 다시 로그인해 주세요.')),
-        );
+        AppNotice.show(context, '비밀번호 변경 완료! 다시 로그인해 주세요.');
         // 비밀번호를 바꿨으니 다시 로그인 화면으로 강제 이동
         Navigator.pushReplacement(
           context,
@@ -48,9 +45,7 @@ class _ChangePasswordScreenState extends State<ChangePasswordScreen> {
         );
       }
     } catch (e) {
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(const SnackBar(content: Text('통신 실패')));
+      AppNotice.show(context, '통신 실패');
     } finally {
       setState(() => _isLoading = false);
     }
diff --git a/lib/ui/admin_dashboard.dart b/lib/ui/admin_dashboard.dart
index 2eba821..183d4e1 100644
--- a/lib/ui/admin_dashboard.dart
+++ b/lib/ui/admin_dashboard.dart
@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/admin_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 import 'login_screen.dart';
 
 // ==========================================
@@ -27,9 +28,7 @@ class _AdminDashboardState extends State<AdminDashboard> {
   Future<void> _resetDatabase() async {
     final message = await _controller.resetDatabase();
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   void _showResetConfirmDialog() {
diff --git a/lib/ui/app_notice.dart b/lib/ui/app_notice.dart
index cb5c138..f51a4e8 100644
--- a/lib/ui/app_notice.dart
+++ b/lib/ui/app_notice.dart
@@ -9,8 +9,13 @@ class AppNotice {
   static final List<_QueuedNotice> _queue = [];
   static bool _showing = false;
 
-  static void show(BuildContext context, String message, {IconData? icon}) {
-    _queue.add(_QueuedNotice(context, message, icon));
+  static void show(
+    BuildContext context,
+    String message, {
+    IconData? icon,
+    Color? color,
+  }) {
+    _queue.add(_QueuedNotice(context, message, icon, color));
     _tryShowNext();
   }
 
@@ -28,6 +33,7 @@ class AppNotice {
       builder: (context) => _NoticeBanner(
         message: next.message,
         icon: next.icon,
+        color: next.color,
         onDone: () {
           entry.remove();
           _showing = false;
@@ -43,17 +49,20 @@ class _QueuedNotice {
   final BuildContext context;
   final String message;
   final IconData? icon;
-  _QueuedNotice(this.context, this.message, this.icon);
+  final Color? color;
+  _QueuedNotice(this.context, this.message, this.icon, this.color);
 }
 
 class _NoticeBanner extends StatefulWidget {
   final String message;
   final IconData? icon;
+  final Color? color;
   final VoidCallback onDone;
 
   const _NoticeBanner({
     required this.message,
     required this.icon,
+    required this.color,
     required this.onDone,
   });
 
@@ -102,7 +111,7 @@ class _NoticeBannerState extends State<_NoticeBanner>
         constraints: const BoxConstraints(maxWidth: 360),
         padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 14),
         decoration: BoxDecoration(
-          color: AppPalette.ink,
+          color: widget.color ?? AppPalette.ink,
           borderRadius: BorderRadius.circular(999),
           boxShadow: [
             BoxShadow(
diff --git a/lib/ui/device_checkout_ledger_page.dart b/lib/ui/device_checkout_ledger_page.dart
index 0c4a65e..47eaae2 100644
--- a/lib/ui/device_checkout_ledger_page.dart
+++ b/lib/ui/device_checkout_ledger_page.dart
@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/device_checkout_ledger_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 
 class DeviceCheckoutLedgerPage extends StatefulWidget {
   final String? teacherId;
@@ -38,26 +39,20 @@ class _DeviceCheckoutLedgerPageState extends State<DeviceCheckoutLedgerPage> {
       teacherName: widget.teacherName ?? '간편인증 선생',
     );
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   Future<void> _reject(int id) async {
     final (_, message) = await _controller.reject(id);
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   // 🖐️ [하드웨어 자동 감지 전까지 임시] 기기를 실제로 돌려받았을 때 누르는 버튼.
   Future<void> _confirmReturn(int id) async {
     final (_, message) = await _controller.confirmReturn(id);
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   ({Color color, String label}) _statusInfo(String status) {
diff --git a/lib/ui/device_checkout_request_screen.dart b/lib/ui/device_checkout_request_screen.dart
index 734be69..c588b17 100644
--- a/lib/ui/device_checkout_request_screen.dart
+++ b/lib/ui/device_checkout_request_screen.dart
@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/device_checkout_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 
 class DeviceCheckoutRequestScreen extends StatefulWidget {
   final String studentId;
@@ -57,9 +58,7 @@ class _DeviceCheckoutRequestScreenState
   Future<void> _submit() async {
     final purpose = _purposeController.text.trim();
     if (_startTime == null || _endTime == null || purpose.isEmpty) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        const SnackBar(content: Text('시작/종료 시각과 사용 목적을 모두 입력해주세요.')),
-      );
+      AppNotice.show(context, '시작/종료 시각과 사용 목적을 모두 입력해주세요.');
       return;
     }
 
@@ -71,9 +70,7 @@ class _DeviceCheckoutRequestScreenState
       endTime: _formatTime(_endTime!),
     );
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
     if (success) Navigator.pop(context);
   }
 
diff --git a/lib/ui/login_screen.dart b/lib/ui/login_screen.dart
index 6ac3348..9395d1d 100644
--- a/lib/ui/login_screen.dart
+++ b/lib/ui/login_screen.dart
@@ -5,6 +5,7 @@ import '../config.dart' show schoolName;
 import '../function/login_controller.dart';
 import '../function/session_store.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 import 'main_dashboard.dart';
 import 'teacher_register_screen.dart';
 
@@ -58,9 +59,7 @@ class _LoginScreenState extends State<LoginScreen> {
           await SessionStore.clear();
         }
         if (!mounted) return;
-        ScaffoldMessenger.of(
-          context,
-        ).showSnackBar(const SnackBar(content: Text('개발자 최고 권한으로 로그인되었습니다.')));
+        AppNotice.show(context, '개발자 최고 권한으로 로그인되었습니다.');
         Navigator.pushReplacement(
           context,
           MaterialPageRoute(
@@ -82,9 +81,7 @@ class _LoginScreenState extends State<LoginScreen> {
         );
         break;
       case LoginOutcome.success:
-        ScaffoldMessenger.of(
-          context,
-        ).showSnackBar(SnackBar(content: Text('${result.name}님 환영합니다!')));
+        AppNotice.show(context, '${result.name}님 환영합니다!');
         _navigateBasedOnRole(
           result.role!,
           result.studentId!,
@@ -150,9 +147,7 @@ class _LoginScreenState extends State<LoginScreen> {
                         onPressed: () async {
                           String newPassword = newPwController.text.trim();
                           if (newPassword.isEmpty) {
-                            ScaffoldMessenger.of(context).showSnackBar(
-                              const SnackBar(content: Text('새 비밀번호를 입력해 주세요.')),
-                            );
+                            AppNotice.show(context, '새 비밀번호를 입력해 주세요.');
                             return;
                           }
 
@@ -167,9 +162,7 @@ class _LoginScreenState extends State<LoginScreen> {
 
                           if (success) {
                             Navigator.pop(dialogContext);
-                            ScaffoldMessenger.of(
-                              context,
-                            ).showSnackBar(SnackBar(content: Text(message)));
+                            AppNotice.show(context, message);
                             _navigateBasedOnRole(
                               role,
                               studentId,
@@ -177,9 +170,7 @@ class _LoginScreenState extends State<LoginScreen> {
                               isDeviceMatched,
                             );
                           } else {
-                            ScaffoldMessenger.of(
-                              context,
-                            ).showSnackBar(SnackBar(content: Text(message)));
+                            AppNotice.show(context, message);
                           }
                         },
                         child: const Text('변경하고 시작하기'),
@@ -269,9 +260,7 @@ class _LoginScreenState extends State<LoginScreen> {
                   MaterialPageRoute(builder: (context) => nextPage),
                 );
               } else {
-                ScaffoldMessenger.of(context).showSnackBar(
-                  const SnackBar(content: Text('비밀번호가 올바르지 않습니다.')),
-                );
+                AppNotice.show(context, '비밀번호가 올바르지 않습니다.');
               }
             },
             decoration: const InputDecoration(
@@ -293,9 +282,7 @@ class _LoginScreenState extends State<LoginScreen> {
                     MaterialPageRoute(builder: (context) => nextPage),
                   );
                 } else {
-                  ScaffoldMessenger.of(context).showSnackBar(
-                    const SnackBar(content: Text('비밀번호가 올바르지 않습니다.')),
-                  );
+                  AppNotice.show(context, '비밀번호가 올바르지 않습니다.');
                 }
               },
               child: const Text('인증하기'),
diff --git a/lib/ui/nfc_poccket_checkin_screen.dart b/lib/ui/nfc_poccket_checkin_screen.dart
index d541f1c..c803b33 100644
--- a/lib/ui/nfc_poccket_checkin_screen.dart
+++ b/lib/ui/nfc_poccket_checkin_screen.dart
@@ -5,6 +5,7 @@ import 'dart:io' show Platform;
 import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:flutter/material.dart';
 import '../function/nfc_pocket_checkin_controller.dart';
+import 'app_notice.dart';
 
 class NfcPocketCheckInScreen extends StatefulWidget {
   final String studentId; // 로그인된 학생 학번 (예: "2061")
@@ -143,9 +144,7 @@ class _NfcPocketCheckInScreenState extends State<NfcPocketCheckInScreen> {
 
   void _showSnackBar(String text, Color color) {
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(text), backgroundColor: color));
+    AppNotice.show(context, text, color: color);
   }
 
   @override
diff --git a/lib/ui/nfc_tag_writer_screen.dart b/lib/ui/nfc_tag_writer_screen.dart
index b435e4d..02db293 100644
--- a/lib/ui/nfc_tag_writer_screen.dart
+++ b/lib/ui/nfc_tag_writer_screen.dart
@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/nfc_tag_writer_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 
 class NfcTagWriterScreen extends StatefulWidget {
   const NfcTagWriterScreen({super.key});
@@ -35,11 +36,11 @@ class _NfcTagWriterScreenState extends State<NfcTagWriterScreen> {
 
   void _showSnackBar(String text, bool isError) {
     if (!mounted) return;
-    ScaffoldMessenger.of(context).showSnackBar(
-      SnackBar(
-        content: Text(text),
-        backgroundColor: isError ? Colors.red : Colors.green,
-      ),
+    AppNotice.show(
+      context,
+      text,
+      color: isError ? Colors.red[700] : Colors.green[700],
+      icon: isError ? Icons.error_outline_rounded : Icons.check_circle_rounded,
     );
   }
 
diff --git a/lib/ui/teacher_register_screen.dart b/lib/ui/teacher_register_screen.dart
index 5e6842a..87ee51f 100644
--- a/lib/ui/teacher_register_screen.dart
+++ b/lib/ui/teacher_register_screen.dart
@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/teacher_register_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 
 class TeacherRegisterScreen extends StatefulWidget {
   const TeacherRegisterScreen({super.key});
@@ -35,9 +36,7 @@ class _TeacherRegisterScreenState extends State<TeacherRegisterScreen> {
     String secret = _secretController.text.trim();
 
     if (id.isEmpty || pw.isEmpty || name.isEmpty || secret.isEmpty) {
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(const SnackBar(content: Text('모든 빈칸을 입력해 주세요.')));
+      AppNotice.show(context, '모든 빈칸을 입력해 주세요.');
       return;
     }
 
@@ -48,9 +47,7 @@ class _TeacherRegisterScreenState extends State<TeacherRegisterScreen> {
       secretCode: secret,
     );
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
     if (success) {
       Navigator.pop(context); // 가입 성공 시 로그인 화면으로 복귀
     }
diff --git a/lib/ui/teacher_student_management_page.dart b/lib/ui/teacher_student_management_page.dart
index 784f74f..0a2673d 100644
--- a/lib/ui/teacher_student_management_page.dart
+++ b/lib/ui/teacher_student_management_page.dart
@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import '../function/excel_file_picker.dart';
 import '../function/teacher_student_management_controller.dart';
 import '../theme/app_palette.dart';
+import 'app_notice.dart';
 
 // 📐 "실시간 출석 확인" 목록(teacher_attendance_page.dart)의 타일 규격과 동일하게 맞춘다.
 const double kAttendanceTileWidth = 220;
@@ -51,9 +52,7 @@ class _TeacherStudentManagementPageState
     final sName = _addNameController.text.trim();
 
     if (sId.isEmpty || sName.isEmpty) {
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(const SnackBar(content: Text('모든 입력란을 채워주세요.')));
+      AppNotice.show(context, '모든 입력란을 채워주세요.');
       return;
     }
 
@@ -69,9 +68,7 @@ class _TeacherStudentManagementPageState
       _addNameController.clear();
       setState(() => _selectedGrade = null);
     }
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   // 📄 [파일 선택 버튼 동작] "파일 선택"으로 엑셀 고르기
@@ -89,16 +86,12 @@ class _TeacherStudentManagementPageState
       rows = _controller.parseExcelBytes(bytes);
     } catch (e) {
       if (!mounted) return;
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(SnackBar(content: Text('엑셀 파일을 읽는 데 실패했습니다: $e')));
+      AppNotice.show(context, '엑셀 파일을 읽는 데 실패했습니다: $e');
       return;
     }
     if (rows.isEmpty) {
       if (!mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
-        const SnackBar(content: Text('유효한 학생 데이터를 찾지 못했습니다. (1행은 머리글로 건너뜁니다)')),
-      );
+      AppNotice.show(context, '유효한 학생 데이터를 찾지 못했습니다. (1행은 머리글로 건너뜁니다)');
       return;
     }
     _showBulkPreviewDialog(rows);
@@ -280,9 +273,7 @@ class _TeacherStudentManagementPageState
       grade: selected,
     );
     if (!mounted) return;
-    ScaffoldMessenger.of(
-      context,
-    ).showSnackBar(SnackBar(content: Text(message)));
+    AppNotice.show(context, message);
   }
 
   // 🔓 [목록 행의 "기기 리셋" 버튼] 학생이 폰을 바꿨을 때 등록 초기화.
@@ -312,9 +303,7 @@ class _TeacherStudentManagementPageState
                 studentName,
               );
               if (!mounted) return;
-              ScaffoldMessenger.of(
-                context,
-              ).showSnackBar(SnackBar(content: Text(message)));
+              AppNotice.show(context, message);
             },
             child: const Text('초기화 승인'),
           ),
@@ -358,9 +347,7 @@ class _TeacherStudentManagementPageState
                 studentId,
               );
               if (!mounted) return;
-              ScaffoldMessenger.of(
-                context,
-              ).showSnackBar(SnackBar(content: Text(message)));
+              AppNotice.show(context, message);
             },
             child: const Text('영구 삭제'),
           ),