An X-ray diagnostic apparatus according to the embodiment includes an X-ray tube (12), an X-ray detector (16), an image generating unit (24) generating time-series medical images of vasoganglion in a predetermined organ, a region setting unit (22) setting a first upstream and downstream regions of a stenosis location in a first blood vessel in the vasoganglion on the images, a curve generating unit (32) generating a stenosis upstream and downstream curves respectively indicating a change in pixel value respectively included in the upstream and downstream regions along the time-series, a stenosis index generating unit (33) generating a stenosis index in the first blood vessel based on the stenosis upstream and downstream curves, and a display unit (23) displaying the stenosis index.
