インストール Chocolatey Windowsのパッケージ管理ツール。 @powershell -NoProfile -ExecutionPolicy unrestricted -Command "iex ((new-object net.webclient).DownloadString('https://chocolatey.org/install.ps1'))" && SET PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin Ruby choco install ruby Ruby Development Kit choco install ruby.devkit Ruby on Rails gem install rails --no-ri --no-rdoc 確認 C:\>rails --version DL is deprecated