1. An X-ray imaging apparatus comprising: a three-dimensional blood-vessel image collecting unit that collects a three-dimensional blood vessel image on which a blood vessel image is enhanced; an X-ray image collecting unit that collects an X-ray image; a composite-image creating unit connected to the three-dimensional blood-vessel image collecting unit and the X-ray image collecting unit for creates creating a three-dimensional projection image projected based on a state of the X-ray imaging apparatus from the three-dimensional blood vessel image collected by the three-dimensional blood-vessel image collecting unit, and creates creating a composite image of created three-dimensional projection image and the X-ray image collected by the X-ray image collecting unit; a displacement determining unit connected to the three-dimensional blood-vessel image collecting unit and the X-ray image collecting unit for determining a displacement caused by inserting an instrument up to the vicinity of an aneurysm between an aneurysm on the three-dimensional projection image and an aneurysm on the X-ray image; and a registration unit connected to the three-dimensional blood-vessel image collecting unit, the X-ray image collecting unit, the composite-image creating unit and the displacement determining unit for correcting the aneurysm position on the three-dimensional blood vessel image by using the displacement determined by the displacement determining unit to generate a corrected three-dimensional blood vessel image so as to match with a position of the aneurysm on the X-ray image, and wherein the composite-image creating unit creates a corrected composite image using the corrected three-dimensional blood vessel image and the X-ray image and displays the corrected composite image onto a display unit.