diff --git a/backend/app/Http/Controllers/Api/ChildrenController.php b/backend/app/Http/Controllers/Api/ChildrenController.php
index 3fe67915..fc21e723 100644
--- a/backend/app/Http/Controllers/Api/ChildrenController.php
+++ b/backend/app/Http/Controllers/Api/ChildrenController.php
@@ -348,7 +348,7 @@ KIKI承知システムを使って「聞いてない！」「言ってない！
         }
 
         if (request()->route()->action['as'] == 'mdp') {
-            if (null === ($params->father_relations = FatherRelation::select($father_relations_select)->where('child_id', (int)$child_id)->first())) {
+            if (null === ($params->father_relations = FatherRelation::select($father_relations_select)->where('child_id', (int)$child_id)->where('father_id', (int)$r->father_id)->first())) {
                 return ['status_code' => 400];
             }
         }