A digital camera is provided with: a diaphragm for controlling an amount of incident light; a solid-state imaging element for receiving the incident light passing through the diaphragm, in which a plurality of pixels are arranged in an array shape, and each of the pixels is divided into a main pixel having a large area and a sub-pixel having a small area by an element separating band deviated from a center of the pixel; a synthesizing process unit for synthesizing a high-sensitivity image signal read from the main pixel of each of the pixels with a low-sensitivity image signal read from the sub-pixel; and controller for separately controlling a gain amount for the high-sensitivity image signal and a gain amount for the low-sensitivity image signal in response to a stop-amount of the diaphragm so as to cause the synthesizing process unit to execute the synthesizing operation.