The invention provides an X-ray diagnostic device, and the device can carry out the positioning more easily relative to a detected object. A mobile X-ray bone mineral measurement device (10) combined with a photographing platform (100) carrying the detected object (102) for use is at least provided with an upper part unit (14) bulging towards the upper side of the photographing platform (100). The upper part unit (14) is provided with one or more positioning marks which are used for the positioning of the mobile X-ray bone mineral measurement device (10) to the detected object (102). For example, each positioning mark comprises a central mark Mc which represents the center of an X-ray scanning region.
