A plurality of LED light sources that are mounted on a front face of a mounting plate are separated from each other respectively being disposed in cells of a partitioning wall. Inner faces of the respective cells are made of a material of low reflectivity. With respect to a normal line direction of the mounting plate, light of the LED light source is viewed, as light being brighter the closer to a back side and darker the closer to a near side on the inner face, in a state of being given gradations by the inner face.