To provide an illumination structure capable of illuminating a tip face and a side face with a desired combination of different illumination colors by improving a degree of freedom of the combination of the illumination color of the tip face of a dial type operation knob and the illumination color of the side face of the operation knob.

The structure comprises: a light-shielding member 17 arranged in a knob internal space 15 to be opened toward a knob tip formation member 9; a first light source 21 arranged inside the light-shielding member 17 as a light source for emitting illumination lights to be transmitted through a light transmission part of the knob tip formation member 9; a second light source 23 arranged in the knob internal space 15 around the light-shielding member 17, and capable of emitting illumination lights with a color different from that of the illumination lights of the first light source 21 as a light source for emitting illumination lights to be transmitted through a light transmission part of a knob side face formation member 7; and a light guide member 19 arranged in the knob internal space 15 around the light-shielding member 17 as a member for introducing the illumination lights emitted by the second light source 23 to the light transmission part of the knob side face formation member 7.