diff --git a/rubygems_plugin.rb b/rubygems_plugin.rb
deleted file mode 100644
index 55c75da..0000000
--- a/rubygems_plugin.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-# frozen_string_literal: true
-
-# If this file is exist, RDoc generates and removes documents by rubygems plugins.
-#
-# In follwing cases,
-# RubyGems directly exectute RDoc::RubygemsHook.generation_hook and RDoc::RubygemsHook#remove to generate and remove documents.
-#
-# - RDoc is used as a default gem.
-# - RDoc is a old version that doesn't have rubygems_plugin.rb.
-
-require_relative 'rdoc/rubygems_hook'
-
-# To install dependency libraries of RDoc, you need to run bundle install.
-# At that time, rdoc/markdown is not generated.
-# If generate and remove are executed at that time, an error will occur.
-# So, we can't register generate and remove to Gem at that time.
-begin
-  require_relative 'rdoc/markdown'
-rescue LoadError
-else
-  Gem.done_installing(&RDoc::RubyGemsHook.method(:generate))
-  Gem.pre_uninstall(&RDoc::RubyGemsHook.method(:remove))
-end