In order to allow an object to easily maintain a posture and a breast to be radiographed, a mammography CT apparatus that radiographs a breast of the object P includes a gantry 10 where a radiation source 104 and a radiation detector 105 are disposed so as to oppose each other. The gantry 10 includes an inclined portion 13 that is inclined in a form of a cone and a planar portion 14 that is formed along an end portion of the inclined portion 13, the planar portion 14 having an opening portion 15 into which the breast of the object P is inserted.
