A digital still camera having a photographing lens system set in a lens tube, a CCD solid image-capturing device, and a mechanical shutter. The mechanical shutter is set on a light path between the photographing lens system and the CCD solid image capturing device. The CCD solid image-capturing device divides a frame of an image into a plurality of fields and transmits the fields serially. The camera compares at least two fields of them, and detects abnormality caused by, for example, abnormal operation of the mechanical shutter or light leakage of the lens body. The camera also displays or announces the abnormality to a user.