PURPOSE: To reduce the deterioration of S/N owing to reference voltage fluctuation noise and sampling noise by receiving the output signals of respective output terminals in first and second sample and hold circuits in a gain control circuit by a differential system.

CONSTITUTION: The same fluctuation noise and sampling noise of reference voltage of field clamping generating in two CCD image sensor output signal sample-and-hold circuits 39 are outputted from the terminals 2 and 3. Noises become an in-phase component by receiving it as a differential input in the gain control circuit 4 composed of a differential amplifier circuit in which the constant current of a next stage is set to be an operation current, and the in-phase removing capacity of the differential input is large since the differential amplifier circuit is used in a constant current source. Thus, a gain control output signal obtained by considerably reducing noise and sampling noise owing to the fluctuation of feed through clamping reference voltage can be obtained.