A portable telephone set housing having an illuminated switch portion. A flexible printed circuit board having a membrane switch and a liquid crystal display is mounted onto a support base of the telephone set housing. Onto the flexible printed circuit board is placed a key top sheet having a plurality of key tops. A switch panel having a plurality of holes for inserting therein of the key tops is mounted onto the key top sheet. The switch panel includes a transparent resin plate having an ink coating formed on the surface thereof except for a portion corresponding to the position of the display portion. In the membrane switch portion of the flexible printed circuit board, a plurality of light emitting diodes are provided which are adapted to introduce light into the interior of the switch panel.