In this breast thickness measurement device and breast thickness measurement method, radiation is radiated from a plurality of different angles to a breast that is in a compressed state, a plurality of image data are generated by means of a radiation detector, and a plurality of tomographic images are generated by reconfiguring on the basis of each image datum after same has been generated. In each tomographic image, the thickness of the compressed breast is calculated on the basis of a tomographic image in which the focal point matches a first marker and a tomographic image in which the focal point matches a second marker.
