In an X-ray imaging apparatus according to an embodiment, a three-dimensional blood-vessel image collecting unit collects a three-dimensional blood vessel image. An X-ray image collecting unit collects an X-ray image. A composite-image creating unit then creates a three-dimensional projection image projected based on a state of the X-ray imaging apparatus from the collected three-dimensional blood vessel image, and creates a composite image of the created three-dimensional projection image and the X-ray image. A displacement determining unit then determines a displacement between an aneurysm on the three-dimensional projection image and the aneurysm on the X-ray image. Subsequently, a registration unit registers the composite image by using the determined displacement, and displays the registered composite image onto a display unit.