PURPOSE: To measure the distance between two communicating points easily and accurately, by adding a distance measuring function to a communication function of a radio set.

CONSTITUTION: When changeover switches S1a, S1b are applied to communication circuit 5 side, communication is possible in a normal communicating state. When the distance of communicating parties is desired to be measured, after mutual discussion with communication, the switches S1a, S1b are changed over to a signal processing circuit 6, and a question signal is transmitted via a switch S2 from an inquiry set. When a response set receives it and a response signal is made at the circuit 6, and this is transmitted from an antenna 1 via a transmission circuit 4, and a transmission/reception automatic switching circuit 2. The inquiry set receives the response signal and this signal is transmitted to a distance measuring circuit 7 via the circuit 6. The circuit 7 measures the distance of the parties for display through the time delay between the transmitted inquiry signal and the received response signal. After a prescribed time, a timer 8 restores the switches S1a, S1b to the circuit 5, to prevent disabled communication due to forgotten switch-off.