Abstract: There is provided a rotating anode X-ray tube capable of efficiently discharging intense heat generated when X-rays are generated and achieving a high output power, a long-time continuous operation and a long operating life of the bearings. A rotating anode X-ray tube is provided with a target, a rotor, a shaft, rolling bearings and a bearing housing for supporting the rolling bearings. An accommodating, section for accommodating Ga or Ga alloy is defined by a center portion of the shaft and an inner surface of the bearing housing between the rolling bearings. Pumping grooves and labyrinth grooves are provided axially outwardly of the accommodating section for preventing the Ga or Ga alloy from leaking.