As one embodiment, the X-ray CT device comprises an X-ray tube, a tube voltage generator, an X-ray detector, a data accumulating unit, and an image processing unit. The tube voltage generator applies tube voltage to the X-ray tube. The tube voltage controlling unit controls the tube voltage generator so as to periodically alternate the tube voltage. The X-ray detector is arranged across a subject from the X-ray tube, and detects the X-rays penetrating the subject. The data accumulating unit accumulates first sampling data when a high voltage is applied to said X-ray tube in one cycle by synchronizing with the change in said tube voltage from the data detected by said X-ray detector, and after a predetermined amount of time has passed from said accumulation, accumulates second sampling data when a low voltage is applied to said X-ray tube. The image processing unit creates images based on the accumulated first sampling data and second sampling data.
