To provide an electron emission element with little power loss.

The electron emission element includes: a cathode electrode 1 in which an electron emission source 2 is arranged on an upper surface; a gate electrode 5 oppositely arranged in parallel with the cathode electrode 1 at a fixed distance d and having an opening 5a where an electron from the electron emission source 2 passes through; and two layers of first and second insulators 3, 4 laminated and intervened between the cathode electrode 1 and the gate electrode 5 and respectively having openings 3a, 4a where electrons from the electron emission source 2 pass through. A dielectric constant 1 of the first insulator 3 closest to the cathode electrode 1 is higher than a dielectric constant 2 of the second insulator 4 next closest to the cathode electrode 1, out of the first and second insulators 3, 4.