In an electron tube, an atomic layer deposition method is used to form an electrical resistance film having a stacked structure of electrically insulating layers and electrically conductive layers or a mixed structure of an electrically insulating material and an electrically conductive material, so as to cover the whole of an inner wall surface and an outer wall surface of a second envelope. By use of the atomic layer deposition method, the firm and fine electrical resistance film with a desired resistance can be formed on an insulation surface, without containing a material such as a binder. When the electrical resistance film is provided with slight electrical conductivity, it can suppress occurrence of withstand voltage failure due to electrification of the insulation surface or the like and realize stability of withstand voltage characteristics.