According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube, X-ray detector, data acquisition circuit, and correction circuit. The X-ray tube generates X-rays. The X-ray detector detects the X-rays. The data acquisition circuit acquires data corresponding to an output from the X-ray detector. The correction circuit executes correction processing for third data acquired by the data acquisition circuit in actual scanning, based on first data acquired by the data acquisition circuit in a state of non-irradiation with X-rays before the actual scanning and second data acquired by the data acquisition circuit in the state of non-irradiation with X-rays after the actual scanning.
