diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..4ef9ab5
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,26 @@
+name: test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Ruby ${{ matrix.ruby }}
+    strategy:
+      matrix:
+        ruby:
+          - '2.6'
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+        bundler-cache: true
+    - name: Run the default task
+      run: bundle exec rake
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b04a8c8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,11 @@
+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+
+# rspec failure tracking
+.rspec_status
diff --git a/.rspec b/.rspec
new file mode 100644
index 0000000..34c5164
--- /dev/null
+++ b/.rspec
@@ -0,0 +1,3 @@
+--format documentation
+--color
+--require spec_helper
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..47b1089
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,10 @@
+AllCops:
+  NewCops: enable
+  SuggestExtensions: false
+  TargetRubyVersion: 2.6
+
+Metrics:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..92ea4b6
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,7 @@
+# Changelog
+
+## Unreleased
+
+### Added
+
+- Initial release.
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..773b34d
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,84 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our community a harassment-free experience for everyone, regardless of age, body size, visible or invisible disability, ethnicity, sex characteristics, gender identity and expression, level of experience, education, socio-economic status, nationality, personal appearance, race, religion, or sexual identity and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming, diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes, and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of acceptable behavior and will take appropriate and fair corrective action in response to any behavior that they deem inappropriate, threatening, offensive, or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, and will communicate reasons for moderation decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when an individual is officially representing the community in public spaces. Examples of representing our community include using an official e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be reported to the community leaders responsible for enforcement at r7kamura@gmail.com. All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing clarity around the nature of the violation and an explanation of why the behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No interaction with the people involved, including unsolicited interaction with those enforcing the Code of Conduct, for a specified period of time. This includes avoiding interactions in community spaces as well as external channels like social media. Violating these terms may lead to a temporary or permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public communication with the community for a specified period of time. No public or private interaction with the people involved, including unsolicited interaction with those enforcing the Code of Conduct, is allowed during this period. Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community standards, including sustained inappropriate behavior,  harassment of an individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 2.0,
+available at https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Community Impact Guidelines were inspired by [Mozilla's code of conduct enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see the FAQ at
+https://www.contributor-covenant.org/faq. Translations are available at https://www.contributor-covenant.org/translations.
diff --git a/Gemfile b/Gemfile
new file mode 100644
index 0000000..b4fb0b5
--- /dev/null
+++ b/Gemfile
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in my_extension.gemspec
+gemspec
+
+gem 'rake', '~> 13.0'
+gem 'rspec', '~> 3.0'
+gem 'rubocop', '~> 1.21'
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 0000000..62d754a
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,58 @@
+PATH
+  remote: .
+  specs:
+    my_extension (0.1.0)
+      rubocop
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ast (2.4.2)
+    diff-lcs (1.5.0)
+    json (2.6.2)
+    parallel (1.22.1)
+    parser (3.1.2.0)
+      ast (~> 2.4.1)
+    rainbow (3.1.1)
+    rake (13.0.6)
+    regexp_parser (2.5.0)
+    rexml (3.2.5)
+    rspec (3.11.0)
+      rspec-core (~> 3.11.0)
+      rspec-expectations (~> 3.11.0)
+      rspec-mocks (~> 3.11.0)
+    rspec-core (3.11.0)
+      rspec-support (~> 3.11.0)
+    rspec-expectations (3.11.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.11.0)
+    rspec-mocks (3.11.1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.11.0)
+    rspec-support (3.11.0)
+    rubocop (1.31.2)
+      json (~> 2.3)
+      parallel (~> 1.10)
+      parser (>= 3.1.0.0)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.18.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.19.1)
+      parser (>= 3.1.1.0)
+    ruby-progressbar (1.11.0)
+    unicode-display_width (2.2.0)
+
+PLATFORMS
+  x86_64-linux
+
+DEPENDENCIES
+  my_extension!
+  rake (~> 13.0)
+  rspec (~> 3.0)
+  rubocop (~> 1.21)
+
+BUNDLED WITH
+   2.3.17
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..c5ca2fd
--- /dev/null
+++ b/README.md
@@ -0,0 +1,11 @@
+# rubocop-extension-template
+
+Custom [RuboCop](https://github.com/rubocop/rubocop) extension template.
+
+## Usage
+
+1. [Use this template](https://github.com/r7kamura/rubocop-extension-template/generate) to create a repository
+2. Rename gem name from `my_extension` to your own
+3. Run `bin/setup`
+4. Add your custom cop by running `bundle exec rake new_cop[Foo/Bar]`
+5. Edit `lib/rubocop/cop/foo/bar.rb`
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..2cc39f9
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'bundler/gem_tasks'
+require 'rspec/core/rake_task'
+
+RSpec::Core::RakeTask.new(:spec)
+
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new
+
+task default: %i[spec rubocop]
+
+desc 'Generate a new cop with a template'
+task :new_cop, [:cop] do |_task, args|
+  require 'rubocop'
+
+  cop_name = args.fetch(:cop) do
+    warn "usage: bundle exec rake 'new_cop[Department/Name]'"
+    exit!
+  end
+
+  generator = RuboCop::Cop::Generator.new(cop_name)
+
+  generator.write_source
+  generator.write_spec
+  generator.inject_require(root_file_path: 'lib/my_extension.rb')
+  generator.inject_config(config_file_path: 'config/default.yml')
+
+  puts generator.todo
+end
diff --git a/bin/console b/bin/console
new file mode 100755
index 0000000..381c37c
--- /dev/null
+++ b/bin/console
@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bundler/setup'
+require 'my_extension'
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+# (If you use this, don't forget to add pry to your Gemfile!)
+# require "pry"
+# Pry.start
+
+require 'irb'
+IRB.start(__FILE__)
diff --git a/bin/setup b/bin/setup
new file mode 100755
index 0000000..dce67d8
--- /dev/null
+++ b/bin/setup
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here
diff --git a/config/default.yml b/config/default.yml
new file mode 100644
index 0000000..88db962
--- /dev/null
+++ b/config/default.yml
@@ -0,0 +1,4 @@
+MyExtension/Example:
+  Description: 'TODO: Write a description of the cop.'
+  Enabled: pending
+  VersionAdded: '0.1'
diff --git a/lib/my_extension.rb b/lib/my_extension.rb
new file mode 100644
index 0000000..07010c3
--- /dev/null
+++ b/lib/my_extension.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'pathname'
+require 'yaml'
+
+require_relative 'my_extension/inject'
+require_relative 'my_extension/version'
+require_relative 'rubocop/cop/my_extension/example'
+
+module MyExtension
+  PROJECT_ROOT = ::Pathname.new(__dir__).parent.expand_path.freeze
+
+  CONFIG_DEFAULT = PROJECT_ROOT.join('config', 'default.yml').freeze
+
+  CONFIG = ::YAML.safe_load(CONFIG_DEFAULT.read).freeze
+
+  private_constant(:CONFIG_DEFAULT, :PROJECT_ROOT)
+end
+
+MyExtension::Inject.defaults!
diff --git a/lib/my_extension/inject.rb b/lib/my_extension/inject.rb
new file mode 100644
index 0000000..a04db3d
--- /dev/null
+++ b/lib/my_extension/inject.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'rubocop'
+
+# The original code is from https://github.com/rubocop/rubocop-rspec/blob/main/lib/rubocop/rspec/inject.rb
+# See https://github.com/rubocop/rubocop-rspec/blob/main/MIT-LICENSE.md
+module MyExtension
+  module Inject
+    def self.defaults!
+      path = CONFIG_DEFAULT.to_s
+      hash = ::RuboCop::ConfigLoader.send(:load_yaml_configuration, path)
+      config = ::RuboCop::Config.new(hash, path).tap(&:make_excludes_absolute)
+      puts "configuration from #{path}" if ::RuboCop::ConfigLoader.debug?
+      config = ::RuboCop::ConfigLoader.merge_with_default(config, path)
+      ::RuboCop::ConfigLoader.instance_variable_set(:@default_configuration, config)
+    end
+  end
+end
diff --git a/lib/my_extension/version.rb b/lib/my_extension/version.rb
new file mode 100644
index 0000000..a908d2f
--- /dev/null
+++ b/lib/my_extension/version.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+module MyExtension
+  VERSION = '0.1.0'
+end
diff --git a/lib/rubocop/cop/my_extension/example.rb b/lib/rubocop/cop/my_extension/example.rb
new file mode 100644
index 0000000..be3e0a8
--- /dev/null
+++ b/lib/rubocop/cop/my_extension/example.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module MyExtension
+      # TODO: Write cop description and example of bad / good code. For every
+      # `SupportedStyle` and unique configuration, there needs to be examples.
+      # Examples must have valid Ruby syntax. Do not use upticks.
+      #
+      # @safety
+      #   Delete this section if the cop is not unsafe (`Safe: false` or
+      #   `SafeAutoCorrect: false`), or use it to explain how the cop is
+      #   unsafe.
+      #
+      # @example EnforcedStyle: bar (default)
+      #   # Description of the `bar` style.
+      #
+      #   # bad
+      #   bad_bar_method
+      #
+      #   # bad
+      #   bad_bar_method(args)
+      #
+      #   # good
+      #   good_bar_method
+      #
+      #   # good
+      #   good_bar_method(args)
+      #
+      # @example EnforcedStyle: foo
+      #   # Description of the `foo` style.
+      #
+      #   # bad
+      #   bad_foo_method
+      #
+      #   # bad
+      #   bad_foo_method(args)
+      #
+      #   # good
+      #   good_foo_method
+      #
+      #   # good
+      #   good_foo_method(args)
+      #
+      class Example < Base
+        # TODO: Implement the cop in here.
+        #
+        # In many cases, you can use a node matcher for matching node pattern.
+        # See https://github.com/rubocop/rubocop-ast/blob/master/lib/rubocop/ast/node_pattern.rb
+        #
+        # For example
+        MSG = 'Use `#good_method` instead of `#bad_method`.'
+
+        # TODO: Don't call `on_send` unless the method name is in this list
+        # If you don't need `on_send` in the cop you created, remove it.
+        RESTRICT_ON_SEND = %i[bad_method].freeze
+
+        # @!method bad_method?(node)
+        def_node_matcher :bad_method?, <<~PATTERN
+          (send nil? :bad_method ...)
+        PATTERN
+
+        def on_send(node)
+          return unless bad_method?(node)
+
+          add_offense(node)
+        end
+      end
+    end
+  end
+end
diff --git a/my_extension.gemspec b/my_extension.gemspec
new file mode 100644
index 0000000..215532c
--- /dev/null
+++ b/my_extension.gemspec
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require_relative 'lib/my_extension/version'
+
+Gem::Specification.new do |spec|
+  spec.name = 'my_extension'
+  spec.version = MyExtension::VERSION
+  spec.authors = ['dummy']
+  spec.email = ['dummy@example.com']
+
+  spec.summary = 'Custom extension for RuboCop.'
+  spec.homepage = 'https://github.com/dummy/my_extension'
+  spec.license = 'MIT'
+  spec.required_ruby_version = '>= 2.6.0'
+
+  spec.metadata['homepage_uri'] = spec.homepage
+  spec.metadata['source_code_uri'] = spec.homepage
+  spec.metadata['changelog_uri'] = "#{spec.homepage}/blob/main/CHANGELOG.md"
+  spec.metadata['rubygems_mfa_required'] = 'true'
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files = Dir.chdir(File.expand_path(__dir__)) do
+    `git ls-files -z`.split("\x0").reject do |f|
+      (f == __FILE__) || f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
+    end
+  end
+  spec.bindir = 'exe'
+  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
+  spec.require_paths = ['lib']
+
+  spec.add_runtime_dependency 'rubocop'
+end
diff --git a/spec/rubocop/cop/my_extension/example_spec.rb b/spec/rubocop/cop/my_extension/example_spec.rb
new file mode 100644
index 0000000..3a3ec12
--- /dev/null
+++ b/spec/rubocop/cop/my_extension/example_spec.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::MyExtension::Example, :config do
+  let(:config) { RuboCop::Config.new }
+
+  # TODO: Write test code
+  #
+  # For example
+  context 'when using `#bad_method`' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        bad_method
+        ^^^^^^^^^^ Use `#good_method` instead of `#bad_method`.
+      RUBY
+    end
+  end
+
+  context 'when using `#good_method`' do
+    it 'registers no offenses' do
+      expect_no_offenses(<<~RUBY)
+        good_method
+      RUBY
+    end
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
new file mode 100644
index 0000000..490b865
--- /dev/null
+++ b/spec/spec_helper.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'my_extension'
+require 'rubocop/rspec/support'
+
+RSpec.configure do |config|
+  config.include RuboCop::RSpec::ExpectOffense
+
+  config.disable_monkey_patching!
+
+  config.raise_errors_for_deprecations!
+
+  config.raise_on_warning = true
+end