According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube, a detector, a first DAS, and a second DAS. The radiation detector includes a plurality of detection elements. Each detection element repeatedly detects X-rays generated by the X-ray tube and transmitted through a subject and repeatedly generates an electrical signal corresponding to the energy of the repeatedly detected X-rays. The first DAS acquires the electrical signal detected by part of the imaging region of each detection element in the integral mode. The second DAS acquires the electrical signal detected by the other part of the imaging region of each detection element in the photon count type mode.
