PURPOSE: To improve S/N deterioration of a multiplication method and to perform a stable discrimination operation by inputting burst signals in a multiplication device after inputting the burst signals in a circuit with trap frequency in image frequency higher than continuous waves.

CONSTITUTION: An output signal of a burst gate circuit 4 is inputted in a trap circuit 12 holding continuous wave frequency of a continuous wave oscillator 7, for example, center frequency in either of B-Y or R-Y signal of the first frequency selective circuits 8 and 10 other than color subcarrier wave frequency (4.43MHz) of a TV signal of a PAL system, for example, trap frequency (4.43+ 0.18=4.61MHz) higher by about 180kHz. As a result, S/N deterioration by the conventional multiplication system can be prevented.