A backlight provides uniform emanating light for a liquid crystal display. In the backlight, light emitted from a light source is incident on a receiving end surface of a light guide plate and emanates through a top surface toward a liquid crystal panel. A bottom surface includes a reflecting hollow wedge extending along the receiving end surface and varying in depth, as measured from the bottom surface, in correspondence with distance from the end surface. A dividing flat portion orthogonal to the reflecting hollow wedge divides the reflecting hollowed portion, and an output surface includes a prism having parallel ridges extending in a direction orthogonal to the receiving end surface.