To provide an X-ray tube appropriate for large output and the manufacturing method thereof by forming a central part of a vacuum container of a metal having excellent heat conductivity and excellent heat radiating property, and forming an X-ray radiating opening in the central part, and brazing a window member made of beryllium for sealing the opening to the periphery of the opening.

A central part for surrounding a positive electrode target 13 of a vacuum container 11, which houses a negative electrode 12 for emitting electron beam and the positive electrode target 13 for generating X-ray, is made of copper or copper alloy having excellent heat conductivity and excellent heat radiating property, and the central part is formed with an X-ray radiating port 14. A window member made of beryllium for sealing the X-ray radiating port 14 is directly brazed to the periphery of the X-ray radiating port by the brazing material with a vacuum heating furnace. Excellent air-tight bonding of the beryllium window member and the vacuum container 11 is thereby obtained, and an X-ray tube having high cooling efficiency and appropriate for large output and large heat capacity and the manufacture thereof can be obtained.