An X-ray diagnostic apparatus according to an embodiment includes an obtaining unit and a calculating unit. The obtaining unit is configured to, with regard to a plurality of X-ray images that are acquired with time by using a contrast media, obtains first transition information that indicates a time-course transition of a signal intensity of the contrast media in a region of interest that corresponds to a blood vessel and obtains second transition information that indicates a time-course transition of the signal intensity of the contrast media in a region to which the contrast media flows earlier than the region of interest. The calculating unit is configured to analyze the first transition information by using the second transition information to calculate blood flow information on each blood flow in the region of interest.
