A computed tomography apparatus is capable of adjusting rotational balance of gantry rotating part in a wide range with easy control. A computed tomography apparatus 100 comprises a rotating part 130 having an X-ray tube 102, a rotating part 130 having an X-ray detector for detecting X-rays from the X-ray tube, at least two mass bodies (M1, M2) provided at the rotating part, movable in the direction of circumference, a driving part 72 for moving at least two mass bodies, a sensor (S) for measuring the vibration of the rotating part and a controller 137 for controlling the driving part for driving the mass bodies on a basis of the outputs of the sensor.