An endoscope comprises a solid-state imaging device having an image area for photoelectric conversion and an optical black area and incorporating an amplification factor varying function. A first signal clamp circuit clamps the analog output signal outputted form the solid-state imaging device with an analog reference signal not influenced by any defective pixel of the optical black area so as to match the output signal with the input range of an analog signal processing circuit. The analog signal processing circuit extracts the signal component photoelectrically converted by the image area from the clamped output signal. The output signal of the analog signal processing circuit clamps the signal of the optical black area by means of a second signal clamp circuit using the output signal of the pixels the number of which is larger than at least the number of pixels in the horizontal direction in the optical black area.
