1. An X-ray diagnostic apparatus characterized by comprising: a bed including a movable table on which a subject to be examined is placed; an X-ray generating unit; an X-ray detection unit; a support which movably supports the X-ray generating unit and the X-ray detection unit; an X-ray application switch which triggers generation of X-rays from the X-ray generating unit; an operation unit for moving the X-ray generating unit and the X-ray detection unit; an image generating unit which generates an image on the basis of an output from the X-ray detection unit; a display unit which is placed near the bed and displays the image; and a simulation image generating unit which generates a simulation image from stored data during a simulation period in accordance with operation of the X-ray application switch and operation of the operation unit.