Immediately before regular image pickup, a reference image is taken through exposure control by center-weighted photometry. A histogram indicative of a luminance distribution of all pixels is generated on the basis of luminance information of the reference image. Then, a luminance point in the histogram where the accumulated number of pixels from the high-luminance side is equal to a half of the total number of pixels is obtained, and a difference is calculated between the luminance point and a luminance point (“118”) when the brightness is uniform in the reference image. At the time of regular image pickup, proper exposure determined in response to the brightness of the subject when the reference image is taken is compensated with the previously calculated difference, and exposure control for the compensated proper exposure is performed.