A three-dimensional light reflection plate that can successfully prevent deformation of the light reflection plate, reduce initial cost and product cost, and facilitate increase in size and reflectance is provided. A light reflection plate includes a bottom plate 12 in which a plurality of mutually parallel slit holes 16 are formed on a flat, light-reflective plate material and a mountain plate 14 that is rectangular from a planar view of which a width direction cross-sectional shape is a mountain shape and in which insertion sections 18 are formed in both width-direction end sections. The mountain plate is fixed to the bottom plate by the insertion sections of the mountain plate being inserted into the slit holes of the bottom plate.
