Generating a right-eye image by combining a right-side capturing image (4° capturing image) of a right breast with a left-side capturing image (0° capturing image) of a left breast rotated by 180° such that the chest walls of the breasts face to each other and a left-eye image by combining a left-side capturing image (0° capturing image) of the right breast with a right-side capturing image (4° capturing image) of the left breast rotated by 180° such that the chest walls of the breasts face to each other. Based on the right-eye and left-eye images generated in the manner described above, displaying a stereoscopic image on a monitor.