In the light-emitting gallium-nitride-group compound semiconductor devices using an insulating substrate, the operating voltage is lowered and at the same time the occurrence of cracks during crystal growth is suppressed, resulting in an improved manufacturing yield rate. The device includes a stacked structure of an n-type layer, a light-emitting layer and a p-type layer formed in the foregoing order on an insulating substrate, and an n-side electrode formed on the surface of the n-type layer. The n-type layer is a laminate layer composed of, in the order from the substrate, a first n-type layer and a second n-type layer having a carrier concentration higher than that of the first n-type layer. As the contact resistance between the n-type layer and the n-side electrode formed thereon is reduced, the operating voltage of a light-emitting device is lowered, and the power consumption decreased.