A light-emitting device according to an embodiment includes a structure for increasing an optical confinement coefficient of a layer forming a resonance mode. The light-emitting device includes a first cladding layer, an active layer, a second cladding layer, a resonance mode formation layer, and a high refractive index layer. The first cladding layer, the active layer, the second cladding layer, the resonance mode formation layer, and the high refractive index layer mainly contain nitride semiconductors. The high refractive index layer has a refractive index higher than that of any of the first cladding layer, the active layer, the second cladding layer, and the resonance mode formation layer, and has a superlattice structure in which two or more layers having refractive indices different from each other are repeatedly laminated.