Random pollution of output signals with logic noise caused by video signal processing is prevented and a high quality image video signal with reduced random noise is output. A signal processor includes a digital signal processor (DSP) which processes a digital signal resulting from analog to digital conversion of an analog signal stored in a pixel unit, an output circuit which outputs a signal resulting from signal processing by the DSP, and line memory which is disposed between the output circuit and the DSP and stores a digital signal output from the DSP for a shorter period than the horizontal scanning period. The output circuit reads the signal stored in the line memory in sync with the beginning of a read-out timing in the horizontal scanning period.