An illumination unit (1, 211) used in a display apparatus provided with the illumination unit (1, 211) that is allowed to output illumination light and a display panel configured to modulate the illumination light based on a picture signal and thereby generate picture light, the illumination unit (1, 211), comprising: an illumination optical system configured to generate the illumination light; and a plurality of lenses configured to reduce a divergence angle of the illumination light, the illumination optical system including a first substrate and a second substrate arranged to be separated from each other and to be opposed to each other, a light source configured to apply light onto an end surface of one of the first substrate and the second substrate, a light modulation layer provided in a gap between the first substrate and the second substrate and configured to exhibit scattering characteristics or transparent characteristics, with respect to the light from the light source, depending on magnitude of an electric field, and electrodes (32, 36) configured to generate an electric field that generates, in the light modulation layer, a plurality of first dot-like scattering regions in a three-dimensional display mode, and to generate an electric field that generates, in the light modulation layer, a plurality of second dot-like scattering regions in a two-dimensional display mode, wherein the first dot-like scattering regions are a part of the second dot-like scattering regions and are arranged side by side in a plurality of lines extending in a first direction, and the second dot-like scattering regions being arranged side by side in a matrix having columns extending in the first direction and rows extending in a second direction intersecting the first direction, the lenses being arranged side by side in the first direction and the second direction, each of the lenses includes a curved surface in one of a light entering surface and a light exiting surface thereof, each of the lenses has a convex shape, and each of the lenses is arranged to cause an apex positions thereof to be opposed to one of the second dot-like scattering regions in a one-to-one relationship. an illumination optical system configured to generate the illumination light; and a plurality of lenses configured to reduce a divergence angle of the illumination light, the illumination optical system including a first substrate and a second substrate arranged to be separated from each other and to be opposed to each other, a light source configured to apply light onto an end surface of one of the first substrate and the second substrate, a light modulation layer provided in a gap between the first substrate and the second substrate and configured to exhibit scattering characteristics or transparent characteristics, with respect to the light from the light source, depending on magnitude of an electric field, and electrodes (32, 36) configured to generate an electric field that generates, in the light modulation layer, a plurality of first dot-like scattering regions in a three-dimensional display mode, and to generate an electric field that generates, in the light modulation layer, a plurality of second dot-like scattering regions in a two-dimensional display mode, wherein the first dot-like scattering regions are a part of the second dot-like scattering regions and are arranged side by side in a plurality of lines extending in a first direction, and the second dot-like scattering regions being arranged side by side in a matrix having columns extending in the first direction and rows extending in a second direction intersecting the first direction, the lenses being arranged side by side in the first direction and the second direction, each of the lenses includes a curved surface in one of a light entering surface and a light exiting surface thereof, each of the lenses has a convex shape, and each of the lenses is arranged to cause an apex positions thereof to be opposed to one of the second dot-like scattering regions in a one-to-one relationship.