A solid-state image-pickup device signal processing apparatus includes a solid-state image-pickup device, an amplifier for amplifying an output signal of the solid-state image-pickup device, an A/D conversion circuit for converting an analog output signal of the amplifier to a digital signal, a digital correlated double sampling circuit for removing noises, and a device for supplying an optional-value direct current signal to a video signal portion of a digital output signal of the A/D conversion circuit. The digital correlated double sampling circuit subtracts a field-through portion of the digital output signal from the video signal portion including the optional-value direct current signal added thereto so that the optional-value direct current signal remains after subtracting the field-through portion from the video signal portion including the optional-value direct current signal when the solid-state image-pickup device image-picks up a dark space.