An edge light display unit includes light generating sources, a substrate mounting the light generating sources, a lens, a diffusion plate expanding light input in a side surface of the diffusion plate as to irradiate a front surface of the diffusion plate, and a heat sink thermally contacted with the substrate. A base portion of the heat sink has a substrate mounting surface and a fin constituting surface substantially perpendicular to the substrate mounting surface. At least one fin extends from the fin constituting surface in a direction substantially perpendicular thereto and along the plurality of light generating sources in a direction parallel to substrate. An air supply and exhaust surface of a cooling air are formed in a back surface side of the display unit.