A light-emitting device includes a first reflective surface, a second reflective surface, a light-emitting layer, and a third reflective surface. The second reflective surface faces the first reflective surface. The light-emitting layer is provided between the first reflective surface and the second reflective surface, and outputs light of a wavelength λ. The third reflective surface faces the second reflective surface, and is located at a distance within λ/4 from the second reflective surface.