PURPOSE: To reduce the amount of interference between cross polarized waves by providing a means inserting a pilot signal to different polarized waves to a transmission side and a means detecting a pilot signal leaked in said polarized wave by using the pilot signal regenerated to a receiving side.

CONSTITUTION: The pilot signal A is inserted to an H polarized wave by using an oscillator at the transmission side and the result is transmitted. The receiving side uses the pilot signal inserted in the H polarized wave and detects a pilot signal B leaked in a V polarized wave receiving signal, forms a signal cancelling the pilot signal detected in the V polarized wave receiving signal by attenuating the H polarized receiving signal at a control circuit 3 and a subtractor 1 subtracts the signal from the V polarized wave. Thus, the interference of the H polarized wave over the V polarized wave is eliminated.