To display a stereoscopic image enabling a viewer to appropriately view the entire image stereoscopically even when the inclination of a detection plane of a radiological image detector is changed depending on the radiographing directions of radiological images constituting a stereoscopic image. The inclination of a detection plane of a radiological image detector is changed depending on radiographing directions and a stereoscopic image is displayed using projected radiological images obtained by projecting radiological images detected on the inclined detection plane onto a plane perpendicular to a desired viewpoint direction of the stereoscopic image.
