rails console require nokogiri return false (but works in irb)

My environment is ruby 1.9.3p327 and rails 3.2.8 on a mac.

I add the gem nokogiri to my Gemfile. Run bundle install command. The command show me Using nokogiri (1.5.5) and the gem list command return nokogiri (1.5.5).

In the rails console require 'nokogiri' return false but in irb it return true.