PURPOSE: To easily elevate vacuum degree of an X-ray tube by constituting a part of a vacuum housing out of a metallic housing, and providing a getter storing part at a part of this housing so as to install a non-deposition getter provided with a heater in vacuum and airtightly.

CONSTITUTION: A vacuum housing 1 is constituted of a cathode side housing 2, a metallic housing 3, and a cathode side housing 4, and the cathode side housing 2 consists of insulating substance and a cathode 5 is mounted and fixed to it, and the anode side housing 4 also consists of insulating material and an anode 6 is mounted to it. In rotating the anode 6, a stator 7 is provided around the cathode side housing 4 and driving force by rotating magnetic field is transmitted to the anode 6 by a power source for driving(not shown in figure). A non-deposition type getter 8 is mounted to a board 32 which constitutes the part of the metallic housing 3 and getter action is performed by heating through current application, and this heating is controlled independently of the power source of the cathode or the anode. For the getter 8, a material nonvolatile and excellent in getter action such as Zn, Ti, Ta, Th, or the like is used, and current application is performed by a heater 81.