A light emitting sheet module includes a light guiding sheet to cover a plurality of key switches, at least one LED disposed on at least one end portion of the light guiding sheet, and a circuit board disposed on the one end portion of the light guiding sheet on which the LED is disposed. When the light emitting sheet module is, mounted on a switch board, it is capable of adaptation to key switches in a wide variety of forms and to illuminate the key switches with light emission of high brightness.