An electron beam emitter comprises an electron emission source capable of emitting electrons; a vacuum chamber containing the electron emission source; and a transmission window that keeps airtightness of the vacuum chamber and is capable of transmitting the electrons from the electron emission source. The transmission window includes a foil that transmits the electrons and a grid that does not transmit the electrons. The electron emission source includes an emission portion that emits the electrons and a non-emission portion that does not emit the electrons. The emission portion has a lower work function than the non-emission portion. The non-emission portion is prepared so as to prevent the electrons from reaching the grid.