Action Controller Overview — Ruby on Rails Guides ↑ここに書いてある。 config/initializers/wrap_parameters.rbはRails4.1だとデフォルトで多分こうなっている。↓ Be sure to restart your server when you modify this file. # This file contains settings for ActionController::ParamsWrapper which # is enabled by default. # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array. ActiveSupport.on_loa