diff --git a/app/Http/Controllers/SettingController.php b/app/Http/Controllers/SettingController.php
index f57d897..7efb103 100644
--- a/app/Http/Controllers/SettingController.php
+++ b/app/Http/Controllers/SettingController.php
@@ -87,7 +87,16 @@ class SettingController extends Controller
     public function storeWebhooks(Request $request)
     {
         $validated = $request->validate([
-            'name' => 'required|string|max:255'
+            'name' => [
+                'required',
+                'string',
+                'max:255',
+                Rule::unique('checkin_webhooks', 'name')->where(function ($query) {
+                    return $query->where('user_id', Auth::id());
+                })
+            ]
+        ], [], [
+            'name' => '名前'
         ]);
 
         if (Auth::user()->checkinWebhooks()->count() >= CheckinWebhook::PER_USER_LIMIT) {
diff --git a/resources/views/setting/webhooks.blade.php b/resources/views/setting/webhooks.blade.php
index 7e62d73..bc181ed 100644
--- a/resources/views/setting/webhooks.blade.php
+++ b/resources/views/setting/webhooks.blade.php
@@ -20,8 +20,11 @@
                     {{ csrf_field() }}
                     <div class="form-group">
                         <label for="name">名前 (メモ)</label>
-                        <input id="name" class="form-control" name="name" type="text" required>
+                        <input id="name" class="form-control {{ $errors->has('name') ? ' is-invalid' : '' }}" name="name" type="text" required>
                         <small class="form-text text-muted">後で分かるように名前を付けておいてください。</small>
+                        @if ($errors->has('name'))
+                            <div class="invalid-feedback">{{ $errors->first('name') }}</div>
+                        @endif
                     </div>
                     <button class="btn btn-primary" type="submit">新規作成</button>
                 </form>