diff --git a/.github/workflows/verify-on-container-centos.yml b/.github/workflows/verify-on-container-centos.yml
new file mode 100644
index 0000000..6163c8a
--- /dev/null
+++ b/.github/workflows/verify-on-container-centos.yml
@@ -0,0 +1,95 @@
+# https://help.github.com/en/articles/workflow-syntax-for-github-actions
+
+name: Docker container (CentOS)
+
+on:
+- push
+
+jobs:
+  ssh-pem:
+    name: Connect to github.com (PEM format)
+    runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
+    strategy:
+      matrix:
+        os:
+        - ubuntu-16.04
+        - ubuntu-18.04
+        - ubuntu-20.04
+        container:
+        - centos:7
+        - centos:8
+      fail-fast: false
+    steps:
+    - name: Install packages
+      run: |
+        yum install -y git openssh-clients
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PEM }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l /root/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-pkcs8:
+    name: Connect to github.com (PKCS8 format)
+    runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
+    strategy:
+      matrix:
+        os:
+        - ubuntu-16.04
+        - ubuntu-18.04
+        - ubuntu-20.04
+        container:
+        - centos:7
+        - centos:8
+      fail-fast: false
+    steps:
+    - name: Install packages
+      run: |
+        yum install -y git openssh-clients
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_PKCS8 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l /root/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
+  ssh-rfc4716:
+    name: Connect to github.com (RFC4716 format)
+    runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
+    strategy:
+      matrix:
+        os:
+        - ubuntu-16.04
+        - ubuntu-18.04
+        - ubuntu-20.04
+        container:
+        - centos:7
+        - centos:8
+      fail-fast: false
+    steps:
+    - name: Install packages
+      run: |
+        yum install -y git openssh-clients
+    - name: Checkout source codes
+      uses: actions/checkout@v2
+    - name: Install SSH key
+      uses: ./.
+      with:
+        key: ${{ secrets.SSH_KEY_RFC4716 }}
+        known_hosts: ${{ secrets.KNOWN_HOSTS }}
+    - name: print created files
+      run: ls -l /root/.ssh
+    - name: git clone through SSH
+      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
diff --git a/.github/workflows/verify-on-container.yml b/.github/workflows/verify-on-container-ubuntu.yml
similarity index 98%
rename from .github/workflows/verify-on-container.yml
rename to .github/workflows/verify-on-container-ubuntu.yml
index 24a8b36..d290bba 100644
--- a/.github/workflows/verify-on-container.yml
+++ b/.github/workflows/verify-on-container-ubuntu.yml
@@ -1,6 +1,6 @@
 # https://help.github.com/en/articles/workflow-syntax-for-github-actions
 
-name: Docker container
+name: Docker container (Ubuntu)
 
 on:
 - push