The stereoscopic effect of auxiliary lines for making a stereoscopic effect easy to figure out is matched with the stereoscopic effect of a subject included in a stereoscopic image when displaying a stereoscopic image using a radiological image. Auxiliary lines are added to two radiological images for displaying a stereoscopic image. The auxiliary lines are formed by arraying a plurality of grids so as to be viewed in the depth direction. The auxiliary lines are generated according to the compression thickness when compressing the subject to radiograph the subject, the radiographing technique, and the compression pressure when compressing the subject to radiograph the subject.
