PURPOSE: To obtain a radio communication system which enables an interruption given from another slave station without providing a transmission line for control, by accepting the interruption request signal from another slave station for a fixed time when it is detected that no speech sending input is given from a slave station which is under calling.

CONSTITUTION: The aural input given to a speed sending input terminal 2 of a master station 1 is detected by a voice detecting circuit 4. Then "1" is delivered to an AND circuit 5. In this case, if no aural output is given to a receiver 6 from a slave station 15, "1" is supplied to the circuit 5. Then a t1 timer 9 is actuated to switch the receiver 6 to an interruption request signal detecting circuit 12 for a time t1. While a receiver 16 of the station 15 receives the audio signal from the station 1. Then a voice detecting circuit 18 detects the audio signal, and "1" is supplied to an AND circuit 20. In this case, "2" is supplied to the circuit 20 if no aural input is given from a speech sending input terminal 23. Then a t2 timer 26 is actuated to stop the working of a transmitter 28 for a time t2.