A field emission device may comprise: an emitter comprising a cathode electrode and an electron emission source supported by the cathode electrode; an insulating spacer around the emitter, the insulating spacer forming an opening that is a path of electrons emitted from the electron emission source; and/or a gate electrode comprising a graphene sheet covering the opening. A method of manufacturing a gate electrode may comprise: forming a graphene thin film on one surface of a conductive film; forming a mask layer having an etching opening on another surface of the conductive film, wherein the etching opening exposes a portion of the conductive film; partially removing the conductive film through the etching opening to partially expose the graphene thin film; and/or removing the mask layer.