An X-ray computed tomographic apparatus includes a cylindrical rotary base (11) supported so as to be rotatable about a rotational axis, an X-ray tube unit (12) mounted on the rotary base (11), an X-ray detecting unit (13) mounted on the rotary base (11), and a reinforcing ring (15) fixed to an end of the rotary base (11), and having a greater rigidity than the rotary base (11).
