diff --git a/backend/app/Http/Controllers/Api/FatherRelationsController.php b/backend/app/Http/Controllers/Api/FatherRelationsController.php
index ef739009..7b6bfdd6 100644
--- a/backend/app/Http/Controllers/Api/FatherRelationsController.php
+++ b/backend/app/Http/Controllers/Api/FatherRelationsController.php
@@ -15,6 +15,14 @@ use App\Models\Meeting;
 use App\Models\MeetingApprovals;
 
 class FatherRelationsController extends Controller {
+    public function check () {
+        if (FatherRelation::select('id')->where('father_id', (int)session()->get('fathers')['id'])->count() == 0) {
+            return ['status_code' => 401, 'error_messages' => ['契約上限数に達した為、メンバー追加できません。']];
+        }
+
+        return ['status_code' => 200];
+    }
+
     public function register (Request $r) {
         if (!isset($r->father_id)) {
             return ['status_code' => 400, 'error_messages' => ['子の追加に失敗しました。']];
diff --git a/backend/routes/api.php b/backend/routes/api.php
index ede4de6d..f5fc959e 100644
--- a/backend/routes/api.php
+++ b/backend/routes/api.php
@@ -133,6 +133,7 @@ Route::group(['prefix' => 'fathers'], function () {
 
         // FatherRelationsController
         Route::group(['prefix' => 'relations'], function () {
+            Route::get('/check', '\App\Http\Controllers\Api\FatherRelationsController@check');
             Route::post('/register', '\App\Http\Controllers\Api\FatherRelationsController@register');
             Route::put('/updateHireDate/{child_id}', '\App\Http\Controllers\Api\FatherRelationsController@updateHireDate');
             Route::delete('/deleteRelationChild/{child_id}', '\App\Http\Controllers\Api\FatherRelationsController@deleteRelationChild');