To sharply shorten time from the transmission of a radio wave up to the connection of a call and to attain comfortable telephone operation by providing each of a master equipment(ME) and a slave equipment(SE) with storing, judging, detecting, and control means.

An ME 13 and an SE 6 are respectively provided with circuits for mutually executing communication and a telephone line is connected to the ME 13. In a non-calling state, both the ME 13 and SE 6 individually search an idle channel and the searching order is stored in circuits such as ROMs built 111 the ME 13 and the SE 6. A battery 2 is used for a power supply for the SE 6, and when the SE 6 is set up on the ME 13, power with prescribed voltage is supplied from a circuit 8 in the ME 13 to the battery 2. The search timing of the ME 13 is transmitted to the SE 6 by a synchronizing signal and the SE 6 executes channel searching synchronously with the synchronizing signal. Thus a control part 5 can discriminate a channel number in searching.