PURPOSE: To obtain an excellent chroma video quality screen with a simple circuit, by rejecting cross color component which a composite video signal is changed into a black or white signal on screen and avoiding the chroma signal from being fogged to black or white picture.

CONSTITUTION: A signal detection circuit 7 detects at least on of black signal less than a prescribed value on a screen or white signal a prescribed value or more out of chroma signal. The detection signal of this cirucit 7 is inputted and harmonics are picked up in a signal conversion circuit 11. The signal attenuation circuit 11 varies the amount of transmission of chroma signal component with the gate signal of the circuit 10. Thus, the chroma signal component can be attenuated at the transient from black to white or to chroma signal, or chroma to white or black signal.