diff --git a/.github/workflows/check_auto_commits.yml b/.github/workflows/check_auto_commits.yml
index 0fc68b9d..4996fb50 100644
--- a/.github/workflows/check_auto_commits.yml
+++ b/.github/workflows/check_auto_commits.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: validate
         run: |
diff --git a/.github/workflows/check_maintenance_branch.yml b/.github/workflows/check_maintenance_branch.yml
index ace14ff8..7c7a1e25 100644
--- a/.github/workflows/check_maintenance_branch.yml
+++ b/.github/workflows/check_maintenance_branch.yml
@@ -20,7 +20,7 @@ jobs:
     name: "check branch without protocol"
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 0
       - name: Check where changes are made
diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index f58b45c5..fcc409a2 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Tag in case renv or docker files changed
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 0  # OR "2" -> To retrieve the preceding commit.
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5ef3b733..f76259e7 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
       - name: Get tag message
         run: |
           TAG_BODY=$(git tag --contains ${{ github.sha }} -n100 | awk '(NR>1)')
@@ -22,7 +22,7 @@ jobs:
         id: tag-body
       - name: Create Release
         id: create_release
-        uses: actions/create-release@v1
+        uses: actions/create-release@0cb9c9b65d5d1901c1f53e5e66eaf4afd303e70e # v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
diff --git a/.github/workflows/update_website.yml b/.github/workflows/update_website.yml
index acff2afb..ea6130dd 100644
--- a/.github/workflows/update_website.yml
+++ b/.github/workflows/update_website.yml
@@ -14,7 +14,7 @@ jobs:
     name: "add protocol to website"
     steps:
       - name: checkout the repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 2
       - name: Get branch name of latest merged PR targeting main