PURPOSE: To provide an illumination structure for a removable operation section capable of easily adjusting the toning and brightness of the whole operation section including the operation section on a main body side.

CONSTITUTION: A light guide body 6 is arranged in a space between a switch base 4 and the back face 1A of a case 1 generated by a connecting terminal 3, and part 6A of the light guide body 6 is extended to a button illumination section through the switch base 4. The button illumination section can be illuminated by a small electric lamp 8 used as a light source, no excess space in the thickness direction is occupied by the light guide body 6, and the toning and brightness of the whole operation section including the operation section on a main body side can be easily adjusted.