An illumination device is provided and includes: a light guide member; a light source provided on one or more side faces of the light guide member; and a light modulating element including a pair of transparent substrates disposed to oppose each other with a gap therebetween, a first electrode provided on a surface of one of the transparent substrates, a second electrode provided on a surface of the other of the transparent substrates, and a light modulation layer provided in the gap and expressing a scattering property or a transparency to light from the light source in accordance with a magnitude of an electric field. The first electrode, the second electrode, or both thereof is patterned, and a density of pattern of the first electrode, the second electrode, or both thereof to which the patterning is applied is varied depending on a distance from the light source.