PROBLEM TO BE SOLVED: To provide a mammographic tomography apparatus capable of radiography up to a base part of a breast by making a detection area of a radiation detector closer to a subject side.SOLUTION: In a mammographic tomography apparatus comprising: a gantry 2 having a front plate 7 on which a breast inlet/outlet 17 for putting a breast 15 into/out from a breast storage part 3 is opened a radiation generation tube 8 and a radiation detector 11 which are oppositely provided with the breast storage part 3 held therebetween in the gantry 2 and a rotation drive part which rotates the radiation generation tube 8 and the radiation detector 11 at the same angular velocity around a rotation shaft D passing inside the breast storage part 3, an annular gap 14c corresponding to a rotational transfer path of the radiation detector 11 is opened on the inner surface of the front plate 7 between the inner peripheral edge and the outer peripheral edge of the front plate 7, surrounding the periphery of the breast inlet/outlet 17, to provide a radiation shielding body 14 and an end of the radiation detector 11 on a side facing the front plate 7 is made to get into the inner side of the gap 14c.
