PURPOSE: To contrive to enhance productivity and to reduce cost, by a method wherein an upper surface of a key base molded from a resin having a desired color is coated with a coating material of another desired color, and the coated film is irradiated with a laser beam to expose the key base in the shape of a desired character or the like.

CONSTITUTION: A coated key base is prepared, and it is fitted to a pre determined position of a keyboard, whereby the coated film can be irradiated with a laser beam even after assembling the keyboard. The step of indicating a character or the like, namely, marking by irradiating with the laser beam is performed after fitting keys into the keyboard, whereby merits are remarkably augmented. Marking can be performed by using a known laser marker or laser machine tool. Although marking is conducted ordianarily at a rate of one mark per one pulse when using a carbon dioxide gas laser marking maching of the pulse-oscillating system, several times of beam irradiation sre required for one mark here, since the coated film on top of the key is thick.