To provide a field emission electron gun capable of minimizing influence by a peripheral electric potential to electrons emitted from emitters of the outer peripheral part.

This electron gun has plural emitters 104 formed in the plural prescribed parts on a base board 109 composed of a conductor or a semiconductor, an insulating film 105 formed in the residual part on the base board 109, a first gate electrode 101 formed on the insulating film 105 so as to surround the plural emitters 104 at intervals and impressed with first voltage V1, the gate edge part 106 composed of a conductor by being formed on the insulating film 105 so as to surround this first gate electrode 101 by contacting with the outer peripheral surface and a second gate electrode 102 formed on the insulating film 105 so as to surround this gate edge part 106 at a distance and impressed with second voltage V2 lower than V1, and the ratio of a width of the gate edge part 106 to the distance is set to 0.5 to 1.5.