An illumination unit includes: a light modulation layer disposed in a gap between a first transparent substrate and a second transparent substrate, and exhibiting a scattering property or transparency with respect to light from a light source, depending on magnitude of an electric field; and an electrode generating an electric field in the light modulation layer, when a voltage is applied thereto, in which the light modulation layer generates a plurality of strip-like illumination light beams extending in a direction intersecting with a first end surface of the first or second transparent substrate with use of light from the light source, when an electric field for a three-dimensional display mode is applied from the electrode to the light modulation layer, and a light emission area per unit area of each of the strip-like illumination light beams varies with a distance from the light source.