diff --git a/web/app.py b/web/app.py
index 25615cb..4d29c60 100644
--- a/web/app.py
+++ b/web/app.py
@@ -256,26 +256,21 @@ def upload_quiz_master_route():
     try:
         if 'file' not in request.files:
             logger.debug('No file part in the request')
-            flash('No file part')
-            return redirect(request.url)
+            return jsonify({'error': 'No file part in the request'}), 400
         file = request.files['file']
         if file.filename == '':
             logger.debug('No selected file')
-            flash('No selected file')
-            return redirect(request.url)
+            return jsonify({'error': 'No selected file'}), 400
         if file and file.filename.endswith('.csv'):
             uploaded_file_path = os.path.join(app.config['UPLOAD_FOLDER'], file.filename)
             file.save(uploaded_file_path)
             logger.debug(f'File {file.filename} uploaded successfully to {uploaded_file_path}')
-            flash('File uploaded successfully')
-            return redirect(url_for('quiz_master_page_route'))
+            return jsonify({'message': 'File uploaded successfully'})
         logger.debug('Invalid file format')
-        flash('Invalid file format')
-        return redirect(request.url)
+        return jsonify({'error': 'Invalid file format'}), 400
     except Exception as e:
         logger.error(f'Error during file upload: {str(e)}')
-        flash('Error during file upload')
-        return redirect(request.url)
+        return jsonify({'error': 'Error during file upload'}), 500
 
 @app.route('/import_quiz_master', methods=['POST'])
 @login_required
@@ -286,16 +281,13 @@ def import_quiz_master_route():
             logger.debug(f'Starting import of file {uploaded_file_path}')
             process_csv(uploaded_file_path)
             logger.debug('File imported successfully')
-            flash('File imported successfully')
             uploaded_file_path = None  # Reset after processing
-            return redirect(url_for('quiz_master_page_route'))
+            return jsonify({'message': 'File imported successfully'})
         logger.debug('No file uploaded to import')
-        flash('No file uploaded to import')
-        return redirect(url_for('quiz_master_page_route'))
+        return jsonify({'error': 'No file uploaded to import'}), 400
     except Exception as e:
         logger.error(f'Error during file import: {str(e)}')
-        flash('Error during file import')
-        return redirect(url_for('quiz_master_page_route'))
+        return jsonify({'error': 'Error during file import'}), 500
 
 def process_csv(file_path):
     try:
diff --git a/web/templates/quiz_master.html b/web/templates/quiz_master.html
index d087ce8..a84d258 100644
--- a/web/templates/quiz_master.html
+++ b/web/templates/quiz_master.html
@@ -246,41 +246,52 @@
         }
 
         async function uploadCsvFile(event) {
-            event.preventDefault();
-            const form = event.target;
-            const formData = new FormData(form);
+        event.preventDefault();
+        const form = event.target;
+        const formData = new FormData(form);
 
-            try {
-                const response = await fetch('/upload_quiz_master', {
-                    method: 'POST',
-                    body: formData
-                });
-                const result = await response.json();
-                document.getElementById('message').innerText = result.message || result.error;
-                if (!result.error) {
-                    form.reset();
-                }
-            } catch (error) {
-                document.getElementById('message').innerText = 'エラーが発生しました: ' + error.message;
-                console.error('Form submission error:', error);
-            }
-        }
+        try {
+            const response = await fetch('/upload_quiz_master', {
+                method: 'POST',
+                body: formData
+            });
 
-        async function importCsvData() {
-            try {
-                const response = await fetch('/import_quiz_master', {
-                    method: 'POST'
-                });
-                const result = await response.json();
-                document.getElementById('message').innerText = result.message || result.error;
-                if (!result.error) {
-                    fetchQuizMasters();
-                }
-            } catch (error) {
-                document.getElementById('message').innerText = 'エラーが発生しました: ' + error.message;
-                console.error('Form submission error:', error);
+            const result = await response.json();
+
+            if (response.ok) {
+                document.getElementById('message').innerText = result.message || 'File uploaded successfully';
+            } else {
+                document.getElementById('message').innerText = result.error || 'File upload failed';
             }
+
+            if (!result.error) {
+                form.reset();
+            }
+        } catch (error) {
+            document.getElementById('message').innerText = 'エラーが発生しました: ' + error.message;
+            console.error('Form submission error:', error);
         }
+    }
+
+    async function importCsvData() {
+        try {
+            const response = await fetch('/import_quiz_master', {
+                method: 'POST'
+            });
+
+            const result = await response.json();
+
+            if (response.ok) {
+                document.getElementById('message').innerText = result.message || 'File imported successfully';
+                fetchQuizMasters();  // インポート後にクイズマスターを再取得
+            } else {
+                document.getElementById('message').innerText = result.error || 'File import failed';
+            }
+        } catch (error) {
+            document.getElementById('message').innerText = 'エラーが発生しました: ' + error.message;
+            console.error('Form submission error:', error);
+        }
+    }
 
         function closeUpdateModal() {
             document.getElementById('updateModal').style.display = 'none';