PURPOSE: To remove a noise by comparatively deciding a picture element with a large correlation with a video signal and an original signal to be delayed for one horizontal scanning period and a video signal to delay a picture element on the same scanning line with two picture elements and four picture elements and replacing the picture element with the other picture element having a correlation when noise is decided.
CONSTITUTION: A composite input signal is sampled by a sampling frequency four-fold that of a color subcarrier with an A/D converter A, quantized by eight bits and A/D-converted. A second signal to delay the first signal for one horizontal period is delayed further for one horizontal period and made into a third signal. The second and first signals are delayed by four picture elements and made into fourth and fifth signals. A sixth signal to delay the third signal by two picture elements is delayed further by two picture elements and made into a seventh signal. By the signals, the correlation with the picture element, to which the fourth signal adjoins, is compared with a comparative deciding circuit H, and the noise contained in the composite signal is removed by means not to replace the fourth signal with the other signal when the correlation exists and to replace it with the other signal when the correlation exists.