A method of manufacturing a field emission device (FED), which reduces the number of photomask patterning processes and improves the manufacturing yield of the FED, is provided. The method includes steps of sequentially forming a cathode layer, a first insulating layer, and a gate layer on a substrate, forming a protection layer on the gate electrode layer, etching portions of the protection layer and gate electrode to form a plurality of first opening holes where portions of the first insulating layer being exposed through the first opening holes, forming a second insulating layer on the protection layer and on the first opening holes, forming a focus electrode layer on the second insulating layer, forming a photoresist layer on the focus electrode layer, etching a portion of the photoresist layer and a portion of the focus electrode layer to form a second opening hole where a portion of the second insulating layer being exposed through the second opening hole, and forming emitter holes exposing a portion of the cathode layer by etching the exposed surface of the second insulating layer to a bottom surface of the first insulating layer. After removing the photoresist layer electron emission emitters are formed on the cathode layer.