According to one embodiment, an X-ray diagnostic apparatus generating an X-ray image in a region of interest, includes a radiography device and processing circuitry. The radiography device takes a first X-ray image before injection of a contrast medium, and takes a second X-ray image and a third X-ray image after injection of the contrast medium. The processing circuitry generates an output image having pixel values that are ratios of pixel values between a difference between the second X-ray image and the first X-ray image and a difference between the third X-ray image and the first X-ray image.
