diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index e6b6851..1a1a0a2 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -3,7 +3,7 @@ name: "Code Scanning"
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
 
 jobs:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5a19d6f..16ad1e4 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -3,7 +3,7 @@ name: 'Test'
 on:
   push:
     branches:
-      - master
+      - main
     paths-ignore:
       - '**.md'
   pull_request:
diff --git a/README.md b/README.md
index 836bd48..48b98f8 100644
--- a/README.md
+++ b/README.md
@@ -3,15 +3,15 @@ GitHub Actions for mdBook
 </h2>
 
 <div align="center">
-  <img src="https://raw.githubusercontent.com/peaceiris/actions-mdbook/master/images/ogp.jpg" alt="GitHub Actions for mdBook thumbnail" width="500px">
+  <img src="https://raw.githubusercontent.com/peaceiris/actions-mdbook/main/images/ogp.jpg" alt="GitHub Actions for mdBook thumbnail" width="500px">
 </div>
 
-[![license](https://img.shields.io/github/license/peaceiris/actions-mdbook.svg)](https://github.com/peaceiris/actions-mdbook/blob/master/LICENSE)
+[![license](https://img.shields.io/github/license/peaceiris/actions-mdbook.svg)](https://github.com/peaceiris/actions-mdbook/blob/main/LICENSE)
 [![release](https://img.shields.io/github/release/peaceiris/actions-mdbook.svg)](https://github.com/peaceiris/actions-mdbook/releases/latest)
 [![GitHub release date](https://img.shields.io/github/release-date/peaceiris/actions-mdbook.svg)](https://github.com/peaceiris/actions-mdbook/releases)
-![Test](https://github.com/peaceiris/actions-mdbook/workflows/Test/badge.svg?branch=master&event=push)
+![Test](https://github.com/peaceiris/actions-mdbook/workflows/Test/badge.svg?branch=main&event=push)
 [![CodeFactor](https://www.codefactor.io/repository/github/peaceiris/actions-mdbook/badge)](https://www.codefactor.io/repository/github/peaceiris/actions-mdbook)
-[![codecov](https://codecov.io/gh/peaceiris/actions-mdbook/branch/master/graph/badge.svg)](https://codecov.io/gh/peaceiris/actions-mdbook)
+[![codecov](https://codecov.io/gh/peaceiris/actions-mdbook/branch/main/graph/badge.svg)](https://codecov.io/gh/peaceiris/actions-mdbook)
 [![Release Feed](https://img.shields.io/badge/release-feed-yellow)](https://github.com/peaceiris/actions-mdbook/releases.atom)
 
 [rust-lang/mdBook] Setup Action.
@@ -65,7 +65,7 @@ name: github pages
 on:
   push:
     branches:
-      - master
+      - main
 
 jobs:
   deploy:
@@ -185,7 +185,7 @@ The alpine base mdBook Docker image is provided on the following repository.
 
 - [MIT License - peaceiris/actions-mdbook]
 
-[MIT License - peaceiris/actions-mdbook]: https://github.com/peaceiris/actions-mdbook/blob/master/LICENSE
+[MIT License - peaceiris/actions-mdbook]: https://github.com/peaceiris/actions-mdbook/blob/main/LICENSE
 
 
 
diff --git a/release.sh b/release.sh
index 9d1e2ee..b2c2ae0 100755
--- a/release.sh
+++ b/release.sh
@@ -3,8 +3,8 @@
 # fail on unset variables and command errors
 set -eu -o pipefail # -x: is for debugging
 
-if [ "$(git branch --show-current)" != "master" ]; then
-  echo "$0: Current branch is not master" 1>&2
+if [ "$(git branch --show-current)" != "main" ]; then
+  echo "$0: Current branch is not main" 1>&2
   exit 1
 fi
 
@@ -26,7 +26,7 @@ if [ "${res}" = "n" ]; then
 fi
 
 git fetch origin
-git pull origin master
+git pull origin main
 git tag -d v1 || true
 git pull origin --tags
 
@@ -44,5 +44,5 @@ rm -rf ./lib
 git commit -m "chore(release): Remove build assets [skip ci]"
 
 TAG_NAME="v$(jq -r '.version' ./package.json)"
-git push origin master
+git push origin main
 git push origin "${TAG_NAME}"