To provide a method of manufacturing a cold cathode field electron emission element preventing easy adhesion of contaminants on side walls of an opening provided in an insulating layer and preventing deterioration of an electron emission characteristic.

In the method of manufacturing the cold cathode field electron emission element provided with a support body 10, a cathode electrode 11, the insulating layer 12, a gate electrode 13 formed on the insulating layer 12 and having a hole part 14A, the opening 14B formed on the insulating layer 12 and communicated with the hole part 14A, and an electron emitting part 15 provided on the gate electrode 11 exposed in a bottom of the opening 14B, the opening 14B is formed on the insulating layer 12 by a dry etching method and then the side walls of the opening 14B are smoothed.