PURPOSE: To remove surely a periodical impulse noise included in a receiving signal by detecting the impulse noise included in the receiving signal and cancelling the receiving signal only by its generating period on the basis of a delayed receiving signal.

CONSTITUTION: Since various conditions are set up so that the delay time of one period of AC power supply flowing into a power line, receiving signals supplied from a power line interface 1 are successively outputted from a delay element 16f as delayed receiving signals C inverted at their polarity after one period of the AC power supply. The delayed receiving signal C is selected only an impulse noise detecting signal ND generating period and supplied to an adder 17b so as to be added to the receiving signal supplied from the interface 1, so that the periodical impulse noise can be removed.