A diamond field emitter and a fabrication method thereof, in which a pretreatment is performed on a surface of an Si substrate in order that diamond nuclei are uniformly formed on the Si substrate during a diamond deposition, an oxide film such as an SiO2 film is deposited on the pretreated surface of the Si substrate and removed after an etching process so that diamond powder can be selectively remained during the etching process, thus the effect of the surface pretreatment of the Si substrate remains in the selected portion during the etching process, and it is also possible to uniformly deposit the diamond in said portion. According to the present invention, the diamond field emitter having excellent and uniform field emission characteristic can be manufactured because the field emission is easily achieved at a tip shaped field emission section, and, moreover, the diamond placed on an upper end portion of the tip increases electron emission effect.