An X-ray CT apparatus according to this invention comprises X-ray generating unit which irradiates X rays toward a object, detecting unit which detects X rays irradiated from the X-ray generating unit and passed through the object, support unit which supports the X-ray generating unit and the detecting unit, driving unit which rotates the support unit, and control unit which controls the driving unit, accumulates regenerative energy generated when the rotating speed of the support unit is decelerated, and supplies the accumulated regenerative energy to the driving unit to rotate the support unit.