An energy control unit continuously adjusts energy of radiations in one shot emitted by an X-ray irradiation unit. An X-ray detection unit generates a plurality of image data pieces in one shot by detecting the radiations whose energy is continuously adjusted and transmitted through a subject. An image classification unit classifies the plurality of image data pieces generated by the X-ray detection unit into image data generated by the radiations of a high energy side and image data generated by the radiations of a low energy side. An image subtraction unit performs weighting and subtraction on the image data generated by the radiations of the high energy side and the image data generated by the radiations of the low energy side.
