To provide a key remarkably enhanced in hardness to change mechanical characteristic such as wear resistance or the like by forming a titanium film on the gold-plated surface by evaporation.

The surface of a brass plate 10 punched in a key shape is successively plated in the order of copper plating, nickel plating, and gold plating to form a copper plating layer 11, a nickel plating layer 12 and a gold plating layer 13 in layers, and the titanium film 14 is formed on the surface of the gold plating layer 13 by evaporation. The hardness of the surface of the gold plating layer 13 is remarkably enhanced, whereby mechanical characteristics such as wear resistance, scratch resistance and the like are changed to prevent the scratch of the key surface. Further, this key has luxuriousness and fashionable property by gold plating.