A light-emitting device includes a group III nitride semiconductor layer of a multilayer structure consisting of a group III nitride semiconductor having a major surface defined by a nonpolar plane or a semipolar plane and having at least an n-type layer and a p-type layer. A surface of the group III nitride semiconductor layer on a light extraction side is a mirror surface. The light-emitting device may further include a transparent electrode in contact with the surface of the group III nitride semiconductor layer on the light extraction side. In this case, a surface of the transparent electrode on the light extraction side is preferably a mirror surface.