To provide a thin type illumination device diffusing light in a wide range with a small number of light sources to cut down manufacturing cost and running cost low.

This illumination device 10 provided at a front face part of a game machine is provided with an LED 13 used as the light source for irradiating light, a reflector 14 for reflecting light from the light source forward, and a diffusion lens 15 arranged in front of the light source and reflector to diffuse the light, wherein the light from the light source is reflected by the reflector to travel toward the diffusion lens side. The illumination device is further provided with an auxiliary reflector 16 set smaller in area than the reflector and arranged between the light source and the diffusion lens to reflect the light from the light source so as to travel toward the reflector side.