An X-ray-diagnostic apparatus generates time-series first vessel images corresponding to a first direction, and generates second vessel image corresponding to a second direction. The apparatus generates third vessel images corresponding to the second direction, by transforming more than one piece out of the first vessel images based on a blood vessel shape in one of the first vessel images and a blood vessel shape in at least one of the second vessel image, the third vessel image corresponding to respective time phases of the first vessel images. The apparatus generates first color image corresponding to the first direction by using more than one piece out of the first vessel images, and generates second color image corresponding to the second direction by using more than one piece out of the third vessel images. The apparatus displays a stereoscopic image based on the first color-image and the second color image
