A flat lamp device includes lower and upper glass plates facing each other in parallel; spacers interposed between the plates to keep a distance therebetween; a cathode electrode singly formed over the entire upper surface of the lower glass plate; an insulation film formed on the cathode electrode; semiconductor films independently patterned on the insulation at intervals; a catalyst metal layer laminated on a buffer metal layer to improve adhesive force of the catalyst metal formed on the semiconductor films; carbon nano-tubes formed on the catalyst metal layer; a grid electrode installed above the carbon nano-tubes between the plates to guide electron emission from the carbon nano-tubes with a mesh shape having an opening for passage of the emitted electrons; an anode electrode formed below the upper glass plate to accelerate the emitted electrons; and a fluorescent layer formed on a lower surface of the anode electrode.