The present invention is directed to obtaining an image having predetermined brightness, while making the degradation of the image as little as possible. A distance (an irradiation distance d) at which a predetermined amount of reflected light can be obtained is obtained from the guide number Gn of a strobe and the f-stop value F (the focal distance f of a zoom lens). When the strobe is used, it is judged whether or not a subject is positioned within the irradiation distance d. When the irradiation distance d of the strobe is shorter than the distance to the subject, that is, the subject is beyond the irradiation distance d of the strobe, an imaging signal is amplified than usual.