A backlight unit includes a prism sheet (an optical path changing portion and a light gathering portion) having lenses and being disposed to face an output surface of a light guide member, and a plurality of second prism inclined surfaces that are inclined at a predetermined inclination angle with respect to the output surface. Further, a lens surface that gathers light from the second prism inclined surfaces toward a normal line direction of the output surface according to the second prism inclined surfaces is provided, and a central position of the lens surface in a transmitting direction of the light guide member is matched with a central position of its corresponding second prism inclined surface.