PURPOSE: To provide a feel of rubber and to prevent characters from wearing out by molding a nonoperating portion and an operating portion from translucent silicone rubber or the like, and integrating a translucent key top with the operating portion through heat vulcanization molding while interposing a character print layer of the same rubber between them.

CONSTITUTION: A key top 2 is molded through primary vulcanization using translucent silicone rubber, a silicone copolymer, or ethylene propylene rubber. A character print layer 3 containing the same kind of rubber is formed on the back of the key top 2. After drying, unnecessary materials on the edge of the key top are removed. The key top 2 is loaded into an upper mold. Raw translucent rubber of the same kind as the rubber of the key top 2 is set in a lower mold and molded through heat vulcanization. A sheet-shaped nonoperating portion 1a and an operating portion 1b bulging from the nonoperating portion 1a are thus formed. The translucent key top 2 is integrated with the flat top surface of the operating portion 1b through heat vulcanization molding with the character print layer 3 intervening between them. An illuminating rubber key convenient for use during the night and in a dark site can thus be obtained.