An X-ray tube and An X-ray detector are mounted on a gantry rotating unit. A gantry fixing unit supports the gantry rotating unit so as to allow it to rotate about a rotation axis. A cover covers the gantry rotating unit and the gantry fixing unit. At least one outlet for discharging air inside the gantry is formed in the cover at a position shifted from an area squaring facing the outer circumference of the gantry rotating unit along the rotation axis. At least one cooling fan is mounted on the gantry fixing unit so as to be located near at least one outlet, and sends air to at least one outlet.
