According to the present invention, a CCD color image pickup element forms a right and left parallel object images and photoelectrically converts the object images into a object image signal. In this case, the object image signal is analyzed to calculate exposure information on a predetermined photometric area. Then, when an SPM synthesizing section generates a stereo image from the object image signal, a partition area setting section sets the luminance level of a partition are on the basis of the exposure information on the parallel object images, the partition area is a median strip used to arrange monocular images of the parallel object images away from each other.