According to an X-ray diagnostic apparatus, an X-ray tube radiates X-rays. An X-ray collimator adjusts an irradiation region of the X-rays. An X-ray detector includes a first detector and a second detector having a smaller detection area than a detection area of the first detector. The X-ray detector is able to detect the X-rays radiated with the first detector and the second detector at the same time. Processing circuitry generates a synthesized image obtained by synthesizing a first X-ray image generated based on an output from the first detector that detected the X-rays radiated in the irradiation region adjusted, and a second X-ray image generated based on an output from the second detector that detected the X-rays radiated in the irradiation region adjusted, the synthesized image having an image size corresponding to an aspect ratio of the irradiation region. The processing circuitry causes a display to display the synthesized image.