To provide a substrate for light-emitting element, which is capable of sufficiently dissipating heat generation of a light-emitting element solely by a heat dissipation layer disposed in parallel with a light-emitting element-mounting surface of the substrate, which is economically advantageous as compared with thermal vias.
A substrate for light-emitting element, which comprises a substrate main body made of a sintered product of a first glass ceramics composition comprising a glass powder and a ceramics filler, wherein a surface on the side where a light-emitting element is to be mounted, is regarded as its main surface, and parts of wiring conductors for electrically connecting electrodes of the light-emitting element and an external circuit, are provided on the main surface; a heat dissipation layer formed on the substrate main body in such a shape to exclude said parts of wiring conductors and the vicinity around them and the periphery of the main surface, made of a metal material containing silver, having a thickness of from 8 to 50 μm and having a flat surface; and an insulating protective layer formed to cover the entirety of the heat dissipation layer including its edge and having a flat surface.