A digital camera includes an image sensor having an array of CCD (Charge-Coupled Device) cells on which an optical image is focused via a lens and a shutter. The image sensor produces an image signal by photoelectric conversion. The image signal is clamped by an analog front end circuit, which feeds a processed analog signal to an analog-to-digital converter. The resultant digital signal is input to a signal processor. The analog front end circuit switches horizontal scanning lines to be clamped in accordance with image pickup information. The horizontal scanning lines to be clamped lie in an optical black area where a photodiode is included in each CCD cell or an optical black area where the former is not included in the latter.