An X-ray diagnostic apparatus comprises an X-ray image generating unit which generates a series of a plurality of X-ray images associated with a subject to be examined, a storage unit which stores data of a three-dimensional image associated with the subject, an image processing unit which generates data of a two-dimensional blood vessel image from the stored data of the three-dimensional image, a difference processing unit which generates a plurality of difference images by subtracting the X-ray images from each other, and a display unit which superimposes and displays each of the plurality of difference images and the two-dimensional blood vessel image.