A light guide propagates, in a longitudinal direction, light incident on an end surface while reflecting the light on an inner surface and emits the light from a light emission surface. The light guide includes a light reflecting surface substantially facing the light emission surface, and multiple diffusion structures provided on the light reflecting surface to diffuse and reflect light. When the length of a diffusion structure in a direction perpendicular to a longitudinal direction is defined as Wr and the length of the light reflecting surface in a direction perpendicular to a longitudinal direction is defined as Wp, Wr<Wp holds.