A computed tomography apparatus including a gantry rotated along a rail in the shape of a ring is provided. The computed tomography apparatus according to an embodiment includes an x-ray source to radiate x-rays, an x-ray detector to detect the x-rays, a gantry at which the x-ray source and the x-ray detector are mounted, and a rail provided in the shape corresponding to an outer side surface of the gantry, and the gantry is configured to rotate along an inner side surface of the rail.