In an X-ray diagnostic apparatus, a volume 3D image in which a desired blood vessel center line has been extracted is stored in a CT 3D image storage unit, and an X-ray two-dimensional image updated in real time is stored in an X-ray 2D image storage unit. The three-dimensional image is aligned with the X-ray two-dimensional image in an alignment unit. Further, a distal end position of a device and a position thereof after a predetermined time are searched for in a search unit, and the distal end position of the device in the three-dimensional image is calculated in a computing unit. Then, a cross-sectional image of the three-dimensional image is displayed on a monitor.