According to one embodiment, a position determination unit determines a top position at a projection data acquisition start time P by a user instruction. A first angle determination unit determines a first rotational angle at the time P by a user instruction. A second angle determination unit determines a second rotational angle at a top movement start time Q and a time interval from the time Q to the time P. A control unit controls a first driving unit to rotate the X-ray tube, controls a second driving unit to make a top start moving in response to arrival of the X-ray tube at the second rotational angle, and controls a DAS to start acquiring projection data in response to arrival of the top at the top position.
