An X-ray CT apparatus includes: a base; a main frame including a pair of tilt shafts, the main frame being supported in a tiltable manner by the base with a pair of bearings interposed in between, the bearings configured to rotatably support the respective tilt shafts; an X-ray tube and an X-ray detector positioned to face each other; an annular rotor configured to hold the X-ray tube and the X-ray detector, the rotor rotatably supported by the main frame with a bearing interposed in between; and a pair of reinforcement members extended from the main frame. One end of each of the pair of tilt shafts is fixed to the main frame, and the other end of each of the pair of tilt shafts is fixed to the respective reinforcement members.