At the light emission surface of a light-guiding plate, first and second grooves and second grooves are formed. Each of the first grooves has a pair of slope parts, and each slope part has an easy slope and a steep slope. The second grooves intersect the first grooves at predetermined angles. Each of the second grooves has a pair of slope parts, and each slope part has an easy slope and a steep slope. With the first grooves and the second grooves intersecting each other, at the light emission surface, a plurality of minute prisms are formed in flat quadrangular pyramid shapes to be dented toward the surface opposite to the light emission surface of the light-guiding plate.