An X-ray image diagnostic apparatus images a subject with X-rays without increasing the burden on a user, and includes an X-ray image diagnostic apparatus 1, a table 4 on which a subject is placed on the top-surface thereof； an X-ray tube 5 disposed beneath the back side of the table and which emits X-rays； a detector 6 disposed above the table 4 so as to face the X-ray tube 5 and detecting the X-rays emitted from the X-ray tube 5 and penetrating the subject on the table 4； an X-ray tube moving mechanism 12 that moves the X-ray tube 5 in a direction approaching the table 4 and moving away therefrom； a detector moving mechanism 13 that moves the detector 6 in a direction approaching the table 4 and moving away therefrom； and a control unit 14 that controls a distance between the X-ray tube 5 and the detector 6 by controlling action of the X-ray tube moving mechanism 12 and the detector moving mechanism 13.
