Metal-gated Pt field emitter arrays (FEAs) have been manufactured using a dual beam system consisting of focused ion and electron beams. The gate opening in Nb or Au gate layers was produced by physical sputtering using a focused ion beam and subsequent wet etching of the underlying silicon dioxide layer. Deposition of a platinum tip into the gate opening using electron-beam-induced chemical reaction resulted in field emission without any thermal annealing process. After wet etching an enlargement of the gate opening in Nb-gated FEAs was observed due to the beam-induced enhanced etching. In contrast, the smaller gate opening in Au-gated FEAs was easily fabricated because of the suppression of the enhanced etching. Consequently, the gate opening was controlled by selection of the gate metal material. The turn-on voltage for field emission decreased by decreasing the diameter of the gate opening.