The purpose of the present invention is to provide a two-dimensional image display device that generates and displays a tomographic image on a panorama-orthogonal cross-sectional plane, which extends in superior-inferior direction and is orthogonal to a panoramic cross-sectional plane, from three-dimensional image information generated from X-ray CT photographic data of a head and neck region. The panorama-orthogonal cross-sectional plane is shiftable in a mesial-distal direction along the panoramic cross-sectional plane. Furthermore, the panorama-orthogonal cross-sectional plane is tiltable around the line of intersection formed by the panorama-orthogonal cross-sectional plane and a horizontal cross-sectional plane. The image display device displays a tomographic image of the head and neck region that is on the shifted and tilted panorama-orthogonal cross-sectional plane.
