Provided is a high-output light-emitting device capable of emitting a light beam in a single mode. The light-emitting device includes a laminate structure body configured by laminating, in order, a first compound semiconductor layer, an active layer, and a second compound semiconductor layer on a base substrate, a second electrode, and a first electrode. The first compound semiconductor layer has a laminate structure including a first cladding layer and a first light guide layer in order from the base substrate, and the laminate structure body has a ridge stripe structure configured of the second compound semiconductor layer, the active layer, and a portion in a thickness direction of the first light guide layer. Provided that a thickness of the first light guide layer is t1, and a thickness of the portion configuring the ridge stripe structure of the first light guide layer is t1′, 6×10−7 m