A light-emitting device including a plurality of emission layers, which has improved luminous efficiency and improved emission lifetime, is provided. In the light-emitting device, a first optical film thickness range L.sub.1 from a light-emitting position of a first emission layer to a light-emitting surface of the device, a second optical film thickness range L.sub.2 from a light-emitting position of a second emission layer to the device light-emitting surface, and film thicknesses of a plurality of layers between the light-emitting surface and the first emission layer, the first emission layer and the second emission layer are set so as to increase the luminous intensity of color of an emission produced by mixing an emission from the first emission layer with an emission from the second emission layer.