An image processing method is provided as one for creating a fused image automatically and with high overlapping accuracy. An image processing method according to an embodiment of the present invention includes (a) a voxel normalization step of equalizing voxel sizes and numbers of voxels in respective effective fields of view of a first 3D image based ON a plurality of first tomographic images obtained from an arbitrary part of a subject and a second 3D image based ON a plurality of second tomographic images obtained from the same part and thereby creating a first normalized 3D image corresponding to the first 3D image and a second normalized 3D image corresponding to the second 3D image and (b) a fused image creation step of creating a fused image and using the first normalized 3D image and the second normalized 3D image.
