According to one embodiment, a rotating anode X-ray tube includes a cathode, an anode target, a sliding bearing including a rotor, a stationary shaft and a lubricant, and a vacuum tube. The rotor includes a bearing member formed to extend along a rotating axis and positioned to surround the stationary shaft. At least one of the stationary shaft and the bearing member are formed of tungsten carbide, silicon carbide, or titanium carbide.