An electron emission device includes a substrate, a plurality of cathode electrodes formed on the substrate, a plurality of electron emission regions electrically coupled to the cathode electrodes, an insulating layer formed on the substrate while covering the cathode electrodes, and a plurality of gate electrodes formed on the insulating layer and crossing the cathode electrodes. The insulating layer is provided with a plurality of openings exposing the corresponding electron emission regions, each of the openings having at least two opening portions that communicate with each other and are different in a size from each other. The gate electrodes are provided with openings communicating with the corresponding openings of the insulating layer. The two opening portions may include a gap in the insulating layer where the gate and cathode electrodes interesect.