diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b82dfa9..2a9a6fc 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -4,7 +4,7 @@ on:
   push:
     branches: [ master, v1.1, build-test ]
   schedule:
-    - cron:  '19 19 */3 * *'
+    - cron:  '5 15 1,15,31 * *'
 
 jobs:
   build:
@@ -30,6 +30,8 @@ jobs:
         run: composer build
 
       - name: commit and push
+        env:
+          TZ: 'Asia/Tokyo'
         run: |
           git add -N .
           if ! git diff --exit-code --quiet
@@ -37,6 +39,6 @@ jobs:
             git config user.email "matsuoshi@gmail.com"
             git config user.name "from GitHub Actions"
             git add --all
-            git commit -m "update holidays"
+            git commit -m "$(date +'%Y-%m-%d %H:%M:%S')"
             git push
           fi
diff --git a/app/holidaysJP.php b/app/holidaysJP.php
index e4c8328..ade9420 100644
--- a/app/holidaysJP.php
+++ b/app/holidaysJP.php
@@ -48,6 +48,8 @@ public function generate()
         foreach ($yearly as $year => $ary) {
             $this->generate_api_file($ary, $year);
         }
+
+        $this->updateCheckedFile();
     }
 
     /**
@@ -165,4 +167,10 @@ protected function output_csv_file($filename, $data)
         }
         fclose($fp);
     }
+
+    protected function updateCheckedFile()
+    {
+        $checkedFile = self::DIST . '/checked_at.txt';
+        file_put_contents($checkedFile, date('Y-m-d H:i:s'));
+    }
 }
diff --git a/docs/v1/checked_at.txt b/docs/v1/checked_at.txt
new file mode 100644
index 0000000..49e7c34
--- /dev/null
+++ b/docs/v1/checked_at.txt
@@ -0,0 +1 @@
+2024-01-22 00:17:56
\ No newline at end of file