A base station apparatus for a wireless communication system, provided for a wireless communication system, which includes a plurality of terminal apparatuses capable of wirelessly performing data communication between said terminal apparatuses, which has a plurality of communication modes related to the data communication, and which includes a direct link mode (i) directly performed between said terminal apparatuses and (ii) having a required communication band smaller than that of another communication mode, as one of the communication modes, said base station apparatus comprising:
- a specifying device for specifying an available communication band from the communication band of the wireless communication system;
- a band information generating device for generating band information indicating the available communication band;
- a base-station-side wireless communicating device for transmitting the band information to at least one portion of the plurality of terminal apparatuses;
- and
- a cancelling device for cancelling the direct link mode by changing the direct link mode to the another communication mode in response to cancellation instruction information indicating to instruct the cancellation of the direct link mode, the direct link mode being associated with said terminal apparatus which is a transmission source of the cancellation instruction information, the cancellation instruction information being generated if a predetermined cancellation condition determined in advance as a condition to cancel the direct link mode is satisfied on each of the plurality of terminal apparatuses, the cancellation instruction information being transmitted through a terminal-side wireless communicating device provided for each of said terminal apparatuses.