Illumination device and game machine

An illumination device comprising:

• a light guide plate unit comprising a light guide plate configured to emit, from a light exit surface, light incident inside from a light incident surface;
• a light projecting unit comprising an optical element configured to supply light to the light guide plate;
• a moving mechanism configured to cause the light guide plate unit to reciprocate in a depth direction;
• a detector comprising a detection region in front of the light guide plate unit in the depth direction, the detector being configured to detect presence or absence of an object without contacting;
• and
• a base configured to support the light guide plate unit, the light projecting unit, the moving mechanism, and the detector, wherein
• the moving mechanism moves the light guide plate unit in accordance with a detection result of the detector.