Almost all current spoken dialog systems treat dialog as that where a single user talks to an agent. On the other hand, we set out to investigate a multiparty dialog system that deals with two agents and a single user. We developed a three person (one user and two agents) and a two person (one user and one agent) dialog system to consider the same dialog tasks, that is, Which do you prefer, udon or ramen (Japanese noodle or Chinese noodle)? and Which do you want to travel to Hokkaido or Okinawa (snowy region or tropical region)? and compared them with respect to user behavior and satisfaction. According to the results of the experiments, the three person dialog system performed better in terms of lively conversation, and user can talk with the agents more like chatting.