An illumination device includes a light source part configured to emit light to a floor surface of a room, a light distribution area setter configured to set a light distribution area of light from the light source part to a first light distribution area or a second light distribution area different from the first light distribution area, and a controller configured to control the light distribution area setter so that light is emitted to the first light distribution area and the second light distribution area in a time-division manner. The second light distribution area set by the light distribution area setter includes a part closer to a corner of the floor surface than the first light distribution area.