To highly accurately position images photographed by different modalities.

The corresponding position 10 of a corresponding anatomical structure between a first standard density distribution model image and a second standard density distribution model image is stored. From the first corresponding position 23 of the corresponding anatomical structure between the first standard density distribution model image and a photographed image for which an object is photographed by a first photographing device and the second corresponding position 33 of the corresponding anatomical structure between the second standard density distribution model image and a photographed image for which the same object is photographed by a second photographing device, the corresponding position of the corresponding anatomical structure between the photographed image obtained by the first photographing device and the photographed image obtained by the second photographing device is obtained.