PURPOSE: To make correspondence to interference removal almost only with basic configuration in the manner of a hardware on the transmission side and without enlarging a frequency band on the reception side by setting the phase, amplitude and control amount of an interference wave by an auxiliary antenna based on whether a frame signal is synchronized or not.

CONSTITUTION: The transmission side is equipped with a frame signal generator 1, adder 2, switch circuit 4, and PSK modulator 5 and the reception side is equipped with a main antenna 7, auxiliary antenna 9, synthesizer 10, delay line 11, phase detector 12, frame detector 13, level decider 14 constituting an interference wave control means, amplitude controller 15, and phase controller 16. On the transmission side, the frame signal is transmitted by a two-phase PSK 5 and on the reception side, a frame synchronizing signal is obtained by detecting delay in the output of synthesizing the main antenna 7 and the auxiliary antenna 8. Then, the reception output phase of the auxiliary antenna is controlled so that the level of an output from the synthesizer 10 can be minimum when frame synchronization is abnormal, and the amplitude of the output from the auxiliary antenna is controlled after obtaining normality of frame synchronization. Thus, the interference wave is removed without requiring any excess transmission band.