An imaging area includes an effective pixel section and an optical black section. Pixel signals read out from the imaging area, onto a plurality of vertical signal lines, are converted by an AD conversion circuit. The converted pixel signals are sequentially input to a signal processing circuit for computing processing. The circuit is provided with a horizontal-stripe noise suppression circuit for averaging of output signals, on a plurality of lines, which are readout from an OB section at an end in the horizontal direction in the imaging area, and for adding and subtracting of the averaged result to effective-pixel signals.