diff --git a/.github/workflows/depup.yml b/.github/workflows/depup.yml
index fe12d03..041eddd 100644
--- a/.github/workflows/depup.yml
+++ b/.github/workflows/depup.yml
@@ -1,7 +1,8 @@
+---
 name: depup
 on:
   schedule:
-    - cron: "14 14 * * *" # Runs at 14:14 UTC every day
+    - cron: 14 14 * * *  # Runs at 14:14 UTC every day
   repository_dispatch:
     types: [depup]
   workflow_dispatch:
@@ -16,4 +17,4 @@ jobs:
           file: action.yml
           version_name: reviewdog_version
           repo: reviewdog/reviewdog
-          labels: "bump:minor"
+          labels: bump:minor
diff --git a/.github/workflows/labels.yml b/.github/workflows/labels.yml
index 1aaf7ee..dc956e9 100644
--- a/.github/workflows/labels.yml
+++ b/.github/workflows/labels.yml
@@ -1,3 +1,4 @@
+---
 name: labels
 on:
   push:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 3fe8750..70cc4ac 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -1,10 +1,11 @@
+---
 name: release
 on:
   push:
     branches:
       - main
     tags:
-      - "v*.*.*"
+      - v*.*.*
   pull_request:
     types:
       - labeled
@@ -19,13 +20,13 @@ jobs:
       # Bump version on merging Pull Requests with specific labels.
       # (bump:major,bump:minor,bump:patch)
       - id: bumpr
-        if: "!startsWith(github.ref, 'refs/tags/')"
+        if: '!startsWith(github.ref, ''refs/tags/'')'
         uses: haya14busa/action-bumpr@v1
 
       # Update corresponding major and minor tag.
       # e.g. Update v1 and v1.2 when releasing v1.2.3
       - uses: haya14busa/action-update-semver@v1
-        if: "!steps.bumpr.outputs.skip"
+        if: '!steps.bumpr.outputs.skip'
         with:
           tag: ${{ steps.bumpr.outputs.next_version }}
 
@@ -33,12 +34,12 @@ jobs:
       - id: tag
         uses: haya14busa/action-cond@v1
         with:
-          cond: "${{ startsWith(github.ref, 'refs/tags/') }}"
+          cond: ${{ startsWith(github.ref, 'refs/tags/') }}
           if_true: ${{ github.ref }}
           if_false: ${{ steps.bumpr.outputs.next_version }}
 
       # Create release
-      - if: "steps.tag.outputs.value != ''"
+      - if: steps.tag.outputs.value != ''
         env:
           TAG_NAME: ${{ steps.tag.outputs.value }}
           BODY: ${{ steps.bumpr.outputs.message }}
diff --git a/.github/workflows/reviewdog.yml b/.github/workflows/reviewdog.yml
index a95461f..0c95f1a 100644
--- a/.github/workflows/reviewdog.yml
+++ b/.github/workflows/reviewdog.yml
@@ -1,3 +1,4 @@
+---
 name: reviewdog
 on:
   push:
@@ -14,8 +15,8 @@ jobs:
         id: reporter
         with:
           cond: ${{ github.event_name == 'pull_request' }}
-          if_true: "github-pr-review"
-          if_false: "github-check"
+          if_true: github-pr-review
+          if_false: github-check
       - uses: reviewdog/action-shellcheck@v1
         with:
           reporter: ${{ steps.reporter.outputs.value }}
@@ -38,6 +39,16 @@ jobs:
           reporter: github-check
           level: warning
 
+  yamllint:
+    name: runner / yamllint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: reviewdog/action-yamllint@v1
+        with:
+          reporter: github-check
+          level: warning
+
   misspell:
     name: runner / misspell
     runs-on: ubuntu-latest
@@ -47,7 +58,7 @@ jobs:
         with:
           reporter: github-check
           level: warning
-          locale: "US"
+          locale: US
 
   alex:
     name: runner / alex
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7f3bf77..eadc4db 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,3 +1,4 @@
+---
 name: test
 on:
   push:
diff --git a/.yamllint.yml b/.yamllint.yml
new file mode 100644
index 0000000..14ec9cc
--- /dev/null
+++ b/.yamllint.yml
@@ -0,0 +1,12 @@
+---
+extends: default
+
+rules:
+  line-length:
+    max: 120
+  quoted-strings:
+    quote-type: single
+    required: only-when-needed
+  truthy:
+    ignore: |
+      /.github/workflows/*.yml
diff --git a/README.md b/README.md
index e8ffade..ef1ba2d 100644
--- a/README.md
+++ b/README.md
@@ -21,39 +21,40 @@ code review experience.
 ```yaml
 inputs:
   github_token:
-    description: 'GITHUB_TOKEN'
-    default: '${{ github.token }}'
+    description: GITHUB_TOKEN
+    default: ${{ github.token }}
   workdir:
-    description: 'Working directory relative to the root directory.'
-    default: '.'
+    description: Working directory relative to the root directory.
+    default: .
   ### Flags for reviewdog ###
   tool_name:
-    description: 'Tool name to use for reviewdog reporter'
-    default: 'rails_best_practices'
+    description: Tool name to use for reviewdog reporter
+    default: rails_best_practices
   level:
-    description: 'Report level for reviewdog [info,warning,error]'
-    default: 'error'
+    description: Report level for reviewdog [info,warning,error]
+    default: error
   reporter:
-    description: 'Reporter of reviewdog command [github-check,github-pr-review,github-pr-check].'
-    default: 'github-check'
+    description: Reporter of reviewdog command [github-check,github-pr-review,github-pr-check].
+    default: github-check
   filter_mode:
     description: |
       Filtering mode for the reviewdog command [added,diff_context,file,nofilter].
       Default is added.
-    default: 'added'
+    default: added
   fail_on_error:
     description: |
       Exit code for reviewdog when errors are found [true,false]
       Default is `false`.
     default: 'false'
   reviewdog_flags:
-    description: 'Additional reviewdog flags'
+    description: Additional reviewdog flags
     default: ''
   ### Flags for rails_best_practices ###
   rails_best_practices_version:
-    description: 'rails_best_practices version'
+    description: rails_best_practices version
   rails_best_practices_flags:
-    description: 'rails_best_practices flags (rails_best_practices --without-color --silent . <rails_best_practices_flags>)'
+    description: |
+      rails_best_practices flags (rails_best_practices --without-color --silent . <rails_best_practices_flags>)
     default: ''
 ```
 
@@ -105,6 +106,7 @@ Supported linters:
 - [reviewdog/action-shellcheck](https://github.com/reviewdog/action-shellcheck)
 - [reviewdog/action-shfmt](https://github.com/reviewdog/action-shfmt)
 - [reviewdog/action-actionlint](https://github.com/reviewdog/action-actionlint)
+- [reviewdog/action-yamllint](https://github.com/reviewdog/action-yamllint)
 - [reviewdog/action-misspell](https://github.com/reviewdog/action-misspell)
 - [reviewdog/action-alex](https://github.com/reviewdog/action-alex)
 
diff --git a/action.yml b/action.yml
index c658e17..fb611a6 100644
--- a/action.yml
+++ b/action.yml
@@ -1,44 +1,46 @@
-name: 'Run rails_best_practices with reviewdog'
-description: '🐶 Run rails_best_practices with reviewdog on pull requests to improve code review experience.'
-author: 'blooper05'
+---
+name: Run rails_best_practices with reviewdog
+description: 🐶 Run rails_best_practices with reviewdog on pull requests to improve code review experience.
+author: blooper05
 inputs:
   github_token:
-    description: 'GITHUB_TOKEN'
-    default: '${{ github.token }}'
+    description: GITHUB_TOKEN
+    default: ${{ github.token }}
   workdir:
-    description: 'Working directory relative to the root directory.'
-    default: '.'
+    description: Working directory relative to the root directory.
+    default: .
   ### Flags for reviewdog ###
   tool_name:
-    description: 'Tool name to use for reviewdog reporter'
-    default: 'rails_best_practices'
+    description: Tool name to use for reviewdog reporter
+    default: rails_best_practices
   level:
-    description: 'Report level for reviewdog [info,warning,error]'
-    default: 'error'
+    description: Report level for reviewdog [info,warning,error]
+    default: error
   reporter:
-    description: 'Reporter of reviewdog command [github-check,github-pr-review,github-pr-check].'
-    default: 'github-check'
+    description: Reporter of reviewdog command [github-check,github-pr-review,github-pr-check].
+    default: github-check
   filter_mode:
     description: |
       Filtering mode for the reviewdog command [added,diff_context,file,nofilter].
       Default is added.
-    default: 'added'
+    default: added
   fail_on_error:
     description: |
       Exit code for reviewdog when errors are found [true,false]
       Default is `false`.
     default: 'false'
   reviewdog_flags:
-    description: 'Additional reviewdog flags'
+    description: Additional reviewdog flags
     default: ''
   ### Flags for rails_best_practices ###
   rails_best_practices_version:
-    description: 'rails_best_practices version'
+    description: rails_best_practices version
   rails_best_practices_flags:
-    description: 'rails_best_practices flags (rails_best_practices --without-color --silent . <rails_best_practices_flags>)'
+    description: |
+      rails_best_practices flags (rails_best_practices --without-color --silent . <rails_best_practices_flags>)
     default: ''
 runs:
-  using: 'composite'
+  using: composite
   steps:
     - uses: reviewdog/action-setup@v1
       with:
@@ -64,5 +66,5 @@ runs:
 
 # Ref: https://haya14busa.github.io/github-action-brandings/
 branding:
-  icon: 'check-circle'
-  color: 'red'
+  icon: check-circle
+  color: red