X-ray diagnosis apparatus including processing circuitry to select a roadmap image based on pixel values

An X-ray diagnosis apparatus includes an X-ray tube, an X-ray detector, and a processing circuitry. The X-ray tube generates X-rays. The X-ray detector detects the X-rays that have passed through a subject. The processing circuitry calculates, for each of a plurality of X-ray images that are acquired chronologically, an average of pixel values and a reference value based on the pixel values. The processing circuitry extracts, from the plurality of X-ray images, an X-ray image with a relatively large difference between the average and the reference value, an X-ray image with a relatively large ratio between the average and the reference value, or an X-ray image with a relatively large number of pixels each representing a value equal to or larger than the average or the reference value.