In the event that the maximum Imax of R, G, B color signals is detected and the maximum value Imax is equal to or higher than the suppression start level Vcs which is lower than a predetermined level to be restricted, a suppression gain is generated in accordance with the value of this maximum Imax, and by this suppression gain Gc, R, G, B color signals to be inputted are simultaneously suppressed. By this, color signals can be restricted to the predetermined range and outputted without impairing white balance.