diff --git a/.github/workflows/monitor_waf_deploy.yml b/.github/workflows/monitor_waf_deploy.yml
index 0af15932..49bdf1cf 100644
--- a/.github/workflows/monitor_waf_deploy.yml
+++ b/.github/workflows/monitor_waf_deploy.yml
@@ -27,7 +27,7 @@ jobs:
         working-directory: sam/waf_rule
     timeout-minutes: 5
     steps: # ref:https://docs.aws.amazon.com/ja_jp/serverless-application-model/latest/developerguide/deploying-using-github.html
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: actions/setup-python@v5
       - uses: aws-actions/setup-sam@v2
       - uses: aws-actions/configure-aws-credentials@v4
@@ -40,7 +40,7 @@ jobs:
       - run: sam deploy --no-confirm-changeset --no-fail-on-empty-changeset
 
         name: sam update
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: actions/setup-python@v5
       - uses: aws-actions/setup-sam@v2
       - uses: aws-actions/configure-aws-credentials@v4
diff --git a/.github/workflows/s3_conversion.yaml b/.github/workflows/s3_conversion.yaml
index d062ebd8..9fb55861 100644
--- a/.github/workflows/s3_conversion.yaml
+++ b/.github/workflows/s3_conversion.yaml
@@ -28,7 +28,7 @@ jobs:
         working-directory: sam/s3-conversion
     timeout-minutes: 60
     steps: # ref:https://docs.aws.amazon.com/ja_jp/serverless-application-model/latest/developerguide/deploying-using-github.html
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
 
       - uses: actions/setup-python@v5