こういうjsonへのシリアライズ方法が書かれてないクラスを使って、to_jsonすると #!/usr/bin/env ruby require 'rubygems' require 'json' class User attr_reader :id, :name def initialize(id, name) @id = id @name = name end end users = Array.new ['user1', 'user2', 'shokai'].each_with_index{|name,id| users.push User.new(id, name) } puts users.to_json クラス名が出てきてしまう ["#<User:0x007fc17b8bda50>","#<User:0x007fc17b8bda28>","#<User:0x007fc17b8bd