In order to follow the ABS conditions when the movement of the object position, such as the movement of an object or the movement of an X-ray tube, occurs during fluoroscopy, an X-ray image diagnostic apparatus includes a histogram generation unit 6b that generates a histogram showing the distribution of brightness values of an X-ray image of an object an object region detection unit 6c that detects an object region, which is a region where the object is imaged, in the X-ray image on the basis of the histogram and an X-ray condition determination unit 2a that determines X-ray conditions defining an output of X-rays so that a brightness value representing the object region approaches a target brightness value of the object region set in advance.
