One embodiment of the present invention addresses the problem of reducing the influence of physiological accumulation in monitoring nuclear medical image data. To solve this problem, the embodiment comprises: extracting a bone area from CT image data having been positioned with nuclear medical image data; in the nuclear medical image data, displaying the data of an area overlapping the bone area extracted above; and, in the nuclear medical image data, not displaying the data of an area not overlapping the bone area extracted above.