diff --git a/.github/labeler.yml b/.github/labeler.yml
index 152ce6f8..3846a6b5 100644
--- a/.github/labeler.yml
+++ b/.github/labeler.yml
@@ -4,7 +4,7 @@ go:
 
 ruby:
   - changed-files:
-      - any-glob-to-any-file: "gem/**/*"
+      - any-glob-to-any-file: "_gem/**/*"
 
 ruby_h_to_go:
   - changed-files:
diff --git a/Gemfile b/Gemfile
index 50c737bc..e570bdf4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -23,4 +23,4 @@ group :test do
   gem "test-unit"
 end
 
-gemspec path: "./gem/"
+gemspec path: "./_gem/"
diff --git a/Gemfile.lock b/Gemfile.lock
index 5e3697ce..03804842 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,5 +1,5 @@
 PATH
-  remote: gem
+  remote: _gem
   specs:
     go_gem (0.2.3)
 
diff --git a/Rakefile b/Rakefile
index 9b7e4fb3..82636b36 100644
--- a/Rakefile
+++ b/Rakefile
@@ -5,11 +5,11 @@ def repo_root
   __dir__
 end
 
-Dir["#{__dir__}/tasks/*.rake"].each { |f| load f }
+Dir["#{__dir__}/_tasks/*.rake"].each { |f| load f }
 
 desc "Release package"
 task :release do
-  Dir.chdir(File.join(__dir__, "gem")) do
+  Dir.chdir(File.join(__dir__, "_gem")) do
     sh "rake release"
   end
 end
diff --git a/Steepfile b/Steepfile
index 1676c605..143e53ba 100644
--- a/Steepfile
+++ b/Steepfile
@@ -4,7 +4,7 @@
 
 target :lib do
   signature "ruby/testdata/example/sig"
-  signature "gem/sig"
+  signature "_gem/sig"
 
   check "ruby/testdata/example/lib" # Directory name
   # check "Gemfile"                   # File name
diff --git a/gem/.gitignore b/_gem/.gitignore
similarity index 100%
rename from gem/.gitignore
rename to _gem/.gitignore
diff --git a/gem/.rspec b/_gem/.rspec
similarity index 100%
rename from gem/.rspec
rename to _gem/.rspec
diff --git a/gem/LICENSE.txt b/_gem/LICENSE.txt
similarity index 100%
rename from gem/LICENSE.txt
rename to _gem/LICENSE.txt
diff --git a/gem/README.md b/_gem/README.md
similarity index 100%
rename from gem/README.md
rename to _gem/README.md
diff --git a/gem/Rakefile b/_gem/Rakefile
similarity index 100%
rename from gem/Rakefile
rename to _gem/Rakefile
diff --git a/gem/bin/console b/_gem/bin/console
similarity index 100%
rename from gem/bin/console
rename to _gem/bin/console
diff --git a/gem/bin/setup b/_gem/bin/setup
similarity index 100%
rename from gem/bin/setup
rename to _gem/bin/setup
diff --git a/gem/go_gem.gemspec b/_gem/go_gem.gemspec
similarity index 100%
rename from gem/go_gem.gemspec
rename to _gem/go_gem.gemspec
diff --git a/gem/lib/go_gem.rb b/_gem/lib/go_gem.rb
similarity index 100%
rename from gem/lib/go_gem.rb
rename to _gem/lib/go_gem.rb
diff --git a/gem/lib/go_gem/mkmf.rb b/_gem/lib/go_gem/mkmf.rb
similarity index 100%
rename from gem/lib/go_gem/mkmf.rb
rename to _gem/lib/go_gem/mkmf.rb
diff --git a/gem/lib/go_gem/version.rb b/_gem/lib/go_gem/version.rb
similarity index 100%
rename from gem/lib/go_gem/version.rb
rename to _gem/lib/go_gem/version.rb
diff --git a/gem/sig/go_gem.rbs b/_gem/sig/go_gem.rbs
similarity index 100%
rename from gem/sig/go_gem.rbs
rename to _gem/sig/go_gem.rbs
diff --git a/gem/sig/go_gem/mkmf.rbs b/_gem/sig/go_gem/mkmf.rbs
similarity index 100%
rename from gem/sig/go_gem/mkmf.rbs
rename to _gem/sig/go_gem/mkmf.rbs
diff --git a/gem/spec/go_gem/mkmf_spec.rb b/_gem/spec/go_gem/mkmf_spec.rb
similarity index 100%
rename from gem/spec/go_gem/mkmf_spec.rb
rename to _gem/spec/go_gem/mkmf_spec.rb
diff --git a/gem/spec/spec_helper.rb b/_gem/spec/spec_helper.rb
similarity index 100%
rename from gem/spec/spec_helper.rb
rename to _gem/spec/spec_helper.rb
diff --git a/tasks/go.rake b/_tasks/go.rake
similarity index 100%
rename from tasks/go.rake
rename to _tasks/go.rake
diff --git a/tasks/go_gem.rake b/_tasks/go_gem.rake
similarity index 73%
rename from tasks/go_gem.rake
rename to _tasks/go_gem.rake
index 56ac0ada..2f30e5fb 100644
--- a/tasks/go_gem.rake
+++ b/_tasks/go_gem.rake
@@ -3,7 +3,7 @@
 namespace :go_gem do
   desc "Run go_gem test"
   task :test do
-    Dir.chdir(File.join(repo_root, "gem")) do
+    Dir.chdir(File.join(repo_root, "_gem")) do
       sh "rspec"
     end
   end
diff --git a/tasks/patch_for_go_gem.rake b/_tasks/patch_for_go_gem.rake
similarity index 100%
rename from tasks/patch_for_go_gem.rake
rename to _tasks/patch_for_go_gem.rake
diff --git a/tasks/ruby.rake b/_tasks/ruby.rake
similarity index 100%
rename from tasks/ruby.rake
rename to _tasks/ruby.rake
diff --git a/tasks/ruby_h_to_go.rake b/_tasks/ruby_h_to_go.rake
similarity index 100%
rename from tasks/ruby_h_to_go.rake
rename to _tasks/ruby_h_to_go.rake