To provide an illumination device of a switch operating part which can light a plurality of operation knobs inexpensively by reducing the number of parts.

The illumination device of a switch operating part includes: the plurality of operation knobs 21, 22 which cover one end opening of a switch body 10; a single light source 34 which is mounted on the back surface of a circuit board 33; and a cover body 40 which covers the other end opening of the switch body. A plurality of reflection parts 45, 46 which reflect irradiation light from the single light source 34 toward each of the plurality of operation knobs 21, 22 are disposed on the cover body 40.