PURPOSE: To prevent image quality deterioration by detecting a change point of a color signal when the luminance level and color are subjected to change and suppressing the gain of a horizontal contour signal only at the change point of the color signal.

CONSTITUTION: The circuit is provided with a color contour detection circuit 19 detecting a change in a color difference signal between a 2R-G signal (d) and a 2B-G signal (e) and a gain control circuit 17 to control a gain of a horizontal contour signal at a change point of the color difference signal. Thus, a change point of a color signal where a horizontal contour signal (g) is not symmetrical is detected by the contour of the color difference signals d, e and image quality deterioration is prevented by suppressing the contour of the color signal and a horizontal contour signal (g).