The outer peripheral portion of a substrate is provided with a first peripheral edge and a second peripheral edge. The first peripheral edge is provided on the edge portion of a first upper surface of the substrate on which a light-emitting diode element is mounted. The second peripheral edge is formed either on an extension of an imaginary line connecting an edge of the light-emitting facet of the light-emitting diode element and the first peripheral edge or inwardly of the extension. The second peripheral edge is located at a position where the first peripheral edge blocks direct light from the light-emitting diode element. This configuration prevents the second upper surface of the substrate provided between the first peripheral edge and the second peripheral edge from becoming deteriorated due to the direct light.