The cathode for photo-electron emission 5 is comprised of an alkali metal containing layer 5d made of material for emitting photo-electrons by the entry of light or for emitting secondary electrons by the entry of electrons, such as particles which consist of an alkali antimony compound, on an Ni electrode substrate 5c on which an Al layer 5b is deposited, and has an intermediate layer 5a made of carbon nano-tubes between the alkali metal containing layer 5d and the Ni electrode substrate 5c, therefore the defect density inside the particles is decreased, and the recombining probability of electrons and holes drops remarkably, which improves the quantum efficiency.