An X-ray tube 1 comprises of a valve 10 joined to an envelope main body 4 at one end side thereof and having an inner cylinder portion 10a extending inwardly at the other end side thereof, a metal tube 11 having an extension portion 11a abutting against the inner cylinder portion 10a on the outer periphery of one end side thereof and projecting to the outside of the valve 10 through the inner cylinder portion 10a at the other end side thereof, and a target supporter 12 supporting a target T at the one end side thereof and inserted into the metal tube 11 at the other side thereof. The inner cylinder portion 10a of the valve 10 and the extension portion 11a of the metal tube 11 are fuse-bonded to each other, and the target supporter 12 is welded to the end portion of the metal tube 11 projecting from the valve 10.