In order to achieve accurate detection of a body motion of a subject in the case where the subject may possibly move between imaging operations, such as during long-length imaging, an imaging information obtaining unit (32) obtains imaging information representing imaging conditions and an imaged subject during the imaging operations, and a local motion vector calculation unit 34 calculates local motion vectors in an overlapping area between each two adjacent radiographic images based on the imaging information. A body motion index value calculation unit 36 calculates a body motion index value with using the local motion vectors based on the imaging information. Further, a body motion determination unit 38 determines whether or not there is a body motion with using the body motion index value based on the imaging information.
