An X-ray image diagnostic apparatus, comprises: a table on which a subject is placed on the front surface thereof； an X-ray tube that is disposed beneath the table and emits X-rays to the subject； a detector that is disposed above the table so as to face the X-ray tube and detects the X-rays emitted from the X-ray source and penetrating the subject placed on the table； an X-ray tube moving mechanism that moves the X-ray tube in a direction approaching or away from the table； a detector moving mechanism that moves the detector in a direction approaching or away from the table； and a control unit that controls a distance between the X-ray tube and the detector by controlling action of the X-ray tube moving mechanism and the detector moving mechanism.
