To provide an electron emission element emitting electrons with a lower voltage and promoting driving cost reduction and service life elongation.

In the electron emission element, an insulator is formed on the surface of a gate electrode opposite to a cathode electrode and the thickness of the insulator is less than a distance between the cathode electrode and the gate electrode. Thus, a deviation in dielectric constant is caused between the cathode electrode and the gate electrode to favorably concentrate an electric field on a surface of an electron emission source on the cathode electrode.