In a comb-like or wedge-like electron emitting device, an emitter or both an emitter and an anode electrode are processed from a single-crystal silicon thin film of an SOI wafer. The single-crystal silicon thin film in portions other than the processed portion is removed so that the silicon oxide layer is dug down further slightly. A gate electrode for applying an electric field in order to draw electrons out of the emitter is provided in the dug-down portion. When the end and side faces of the emitter are formed as (111) faces by anisotropic etching in the condition that the single-crystal silicon thin film is oriented to a (100) face, the emitter has a sharp edge at about 55.degree. with respect to the substrate. In a conical electron emitting device, the gate electrode is constituted by a single-crystal silicon thin film of an SOI wafer so that a pyramid surrounded by the (111) faces is formed on the single-crystal silicon substrate.