PROBLEM TO BE SOLVED: To provide an X-ray diagnostic apparatus which makes the periphery of an X-ray detector compact to eliminate a variety of limitations: and to provide a detector-fixing unit.SOLUTION: An X-ray diagnostic apparatus includes an X-ray generation part, an X-ray detector 13, a support part, and drive motors 184, 185. The X-ray generation part irradiates a subject with X-rays. The X-ray detector detects X-rays. The support part is set at a position facing the X-ray generation part inside a C-arm supporting the X-ray generation part, has an expansion/contraction mechanism expanding/contracting in a direction of the X-ray generation part for at least two stages, and supports the X-ray detector. The drive motors expand or contract the expansion/contraction mechanism to control the distance between the X-ray generation part and the X-ray detector.
