Provided is an x-ray CT device whereby it is possible to determine simply a reconstruction method corresponding to a photographic condition. An x-ray CT device of an embodiment, which generates an image by receiving a vital signal of a subject and carrying out synchronized photography, comprises an irradiation unit which irradiates a subject with x-rays, a detection unit which detects the x-rays which have passed through the subject, a rotation unit which rotates the irradiation unit and the detection unit in a circumferential periphery of the subject, a storage unit, a computation unit, a determination unit, and a processing unit. The storage unit pre-stores a prescribed threshold value. On the basis of a photographic condition relating to synchronized photography, the computation unit computes a detection data quantity wherein a quantity of detection data which is detected by the detection unit is represented by the number of rotations of the rotation unit. On the basis of the detection data quantity from the computation unit and the threshold value from the storage unit, the determination unit determines a reconstruction process which is carried out on the detection data. The processing unit carries out on the detection data the reconstruction process which is determined by the determination unit and generates an image.Cette invention concerne un tomodensitomètre permettant de déterminer simplement une méthode de reconstruction correspondant à un cliché photographique. Dans un mode de réalisation, le tomodensitomètre qui génère une image après réception dun signe vital émis par un sujet et réalisation dun cliché photographique synchronisé, comprend une unité dirradiation qui envoie des rayons X sur le sujet, une unité de détection qui détecte les rayons X traversant le sujet, une unité de rotation qui fait pivoter lunité dirradiation et lunité de détection selon un cercle circonscrit au sujet, une unité de stockage, une unité de calcul, une unité de détermination
