A digital still camera has a function to perform first and second exposures in a single imaging sequence. In the first exposure, imaging conditions are determined to obtain proper exposure amount of the background with available light. Then, the second exposure is carried out with the flashlight to illuminate the main subject. The photographic sensitivity, the shutter speed, and the aperture value for the second exposure are determined such that the exposure value in the second exposure is under-exposure by two steps or more, compared to that in the first exposure. Images obtained by first and second exposures are synthesized to obtain a composite image.