Positioning images are created by a projection-image creating unit before imaging, and the positioning images are grouped and stored by a projection-image storage unit for each preset. When imaging is started, a positioning-information calculating unit calculates positioning parameters using the positioning images stored in the projection-image storage unit. An analysis-image-for-synthesis creating unit creates an analysis image using the positioning parameters, and an analysis-image synthesizing and displaying unit synthesizes the analysis image with a live image and displays a synthesized image. When an imaging direction of an X-ray angiography apparatus is changed, a positioning-information updating unit directly updates the positioning parameters based on an amount of change of the imaging direction.