To obtain key illumination allowing the exertion of the originality of a user at low cost while maintaining mass production.

This key button illumination structure of an electronic appliance has: two connectable and separable cases 102, 103 forming a casing of the electronic appliance 101; a key button 104 formed by forming a plurality of light-transmissive key tops 108 in a sheet state and fitting the key tops in windows of one case; a color light guide sheet 111 performing the color illumination of the key button by performing light-transmissive color painting on the surface of the sheet to the light-transmissive sheet and lapping the sheet over the the sheet; and a plurality of light-emitting diodes 105 loaded on a board 106 fixed to the other case, emitting white light, and serving as a light source for light guided through the color light guide sheet at the connection of one case.