In general, an X-ray imaging apparatus according to one embodiment includes an X-ray tube, an X-ray detector, and processing circuitry. The processing circuitry is configured to obtain correction-target data that includes component deterioration resulting from a transient response of the X-ray detector, and to output, based on the obtained correction-target and a model that outputs data in which component deterioration resulting from a transient response is reduced based on an input of data that includes component deterioration resulting from a transient response, corrected data in which the component deterioration resulting from the transient response of the X-ray detector is reduced.