After a first wireless terminal device transitions to a Direct Link Protocol mode, the terminal device transmits an ICMP_echo_request signal directly to a second wireless terminal device and, upon receiving an ICMP_echo_reply signal from the second wireless terminal device within a fixed period of time, counts up the number of times there is a reply. If the ICMP_echo_reply signal is not received within a fixed period of time, then the first wireless terminal device counts up the number of non-replies. As a result, the first wireless terminal device can readily judge whether it is capable of communicating directly with the second wireless terminal device in the Direct Link Protocol mode.