Even when one side of a radiological image detector is inclined with respect to a straight line linking two focal positions of radiation, an appropriate stereoscopic image is displayed. The amount d of shift between two radiological images in a direction perpendicular to a parallax direction is acquired and a stereoscopic image is displayed using the two radiological images which are relatively shifted in the direction perpendicular to the parallax direction so that the acquired amount d of shift is reduced.
