According to one embodiment, a rotating-anode X-ray tube assembly includes an X-ray tube, a stator coil, a housing, an X-ray radiation window, and a coolant. The housing includes a first divisional part which includes an X-ray radiation port and to which the X-ray tube is directly or indirectly fixed, and a second divisional part located on a side opposite to an anode target with respect to an anode target rotating mechanism and coupled to the first divisional part. A coupling surface between the first divisional part and the second divisional part is located on one plane, and is inclined to an axis, with exclusion of a direction perpendicular to the axis.