To provide an electron beam tube which has sufficiently high transmissivity of electron beam and small distortion generating on window member and is obtainable of long life of use.

An electron beam tube 10 is provided with an electron beam generator 30 inside a vacuum vessel 20, the vacuum vessel is constituted of a lid member 22 provided so as to cover the front opening of a tube member 21 and having an electron beam path hole, and a window member 24 provided so as to seal the electron beam path hole of the lid member and the electron beam path region is formed. In the window member, the electron beam path region 24a is formed in the part with thickness below 6 μm and the window member is air-tightly welded and contacted with a metal film 25 of thickness below 10 μm on the peripheral surface of the electron beam path hole 23. The window member is desired to be formed in plate shape consisting at least one kind chosen from periodic table 14 family.