An inter-line CCD (IT-CCD) capable of reading signals in two read modes, a field read mode and a frame read mode, is used to control, by a system control means, a CCD exposure and a signal read mode, a short-time exposure signal (Short signal) acquires an image by a field read and a long-time exposure signal (Long signal) acquires an image by a frame read, and these two images are synthesized by a signal synthesizing means to expand a dynamic range.