X-ray diagnostic device

An X-ray diagnostic device (150) according to an embodiment comprises: an X-ray imaging unit; a holding unit (18) which holds the X-ray imaging unit such that an imaging system axis that passes through a focal point of an X-ray tube and a center position of an X-ray detector is rotatable about an isocenter; a display unit (9) which displays a first X-ray image; an operation unit (8) for inputting a target position that corresponds to a site of interest with respect to the first X-ray image; a position of interest calculation unit (4) which calculates a position that corresponds to the site of interest in a second X-ray image on the basis of an angle between the imaging system axis of the second X-ray image that is different from the first X-ray image and the imaging system axis of the first X-ray image, the distance from the isocenter to a top plate (11), and the distance between the target position and the top plate (11); and a top plate movement calculation unit (5) which calculates the movement of the top plate (11) for displaying the site of interest in the same position as the target position in the second X-ray image on the basis of the calculated position, the target position, the angle and the distance from the isocenter to the top plate (11).