A control unit 18 transmits via a processing unit 16 through a wireless unit 12 a participation request to a registrar among multiple other terminal apparatuses forming an ad hoc network. The control unit 18 receives participation approval via the wireless unit 12 through the processing unit 16. The wireless unit 12 through the processing unit 16 all communicate by participating in the ad hoc network when the participation approval is received. The control unit 18 broadcasts a search signal for searching another terminal apparatus to which a role of approving participation of a new terminal apparatus in the ad hoc network is assigned, prior to the transmission of a participation request.