A light-emitting device comprising: a reflective layer; a first electrode disposed on the reflective layer; an organic light emission layer disposed on the first electrode; and a second electrode disposed on the organic light emission layer, wherein the reflective layer and the second electrode constitute a micro cavity having a resonance wavelength, wherein the organic light emission layer comprises a first organic light emission material layer configured to generate a first light of a first wavelength, a second organic light emission material layer configured to generate a second light of a second wavelength different from the first wavelength, and a third organic light emission material layer configured to generate a third light of a third wavelength different from the first and the second wavelengths, wherein the first organic light emission material layer is disposed at a position of a first antinode of the resonance wavelength, and wherein the second organic light emission material layer and the third organic light emission material layer are disposed at a position of a second antinode of the resonance wavelength resonating in the micro cavity, characterised in that the reflective layer comprises a plurality of nanostructures; wherein a width of each of the plurality of nanostructures of the reflective layer, a height of each of the plurality of nanostructures, and a period of the plurality of nanostructures are set such that the resonance wavelength of the micro cavity coincides with the second wavelength or the third wavelength, and wherein the period of the plurality of nanostructures is smaller than the resonance wavelength of the micro cavity, wherein, in the case that the resonance wavelength of the micro cavity coincides with the second wavelength, the first organic light emission material layer is disposed at the position of the first antinode of the second wavelength and the second organic light emission material layer and the third organic light emission material layer are disposed at the position of the second antinode of the second wavelength resonating in the micro cavity, or, in the case that the resonance wavelength of the micro cavity coincides with the third wavelength, the first organic light emission material layer is disposed at the position of the first antinode of the third wavelength and the second organic light emission material layer and the third organic light emission material layer are disposed at the position of the second antinode of the third wavelength resonating in the micro cavity. a reflective layer; a first electrode disposed on the reflective layer; an organic light emission layer disposed on the first electrode; and a second electrode disposed on the organic light emission layer, wherein the reflective layer and the second electrode constitute a micro cavity having a resonance wavelength, wherein the organic light emission layer comprises a first organic light emission material layer configured to generate a first light of a first wavelength, a second organic light emission material layer configured to generate a second light of a second wavelength different from the first wavelength, and a third organic light emission material layer configured to generate a third light of a third wavelength different from the first and the second wavelengths, wherein the first organic light emission material layer is disposed at a position of a first antinode of the resonance wavelength, and wherein the second organic light emission material layer and the third organic light emission material layer are disposed at a position of a second antinode of the resonance wavelength resonating in the micro cavity, wherein a width of each of the plurality of nanostructures of the reflective layer, a height of each of the plurality of nanostructures, and a period of the plurality of nanostructures are set such that the resonance wavelength of the micro cavity coincides with the second wavelength or the third wavelength, and wherein the period of the plurality of nanostructures is smaller than the resonance wavelength of the micro cavity, wherein, in the case that the resonance wavelength of the micro cavity coincides with the second wavelength, the first organic light emission material layer is disposed at the position of the first antinode of the second wavelength and the second organic light emission material layer and the third organic light emission material layer are disposed at the position of the second antinode of the second wavelength resonating in the micro cavity, or, in the case that the resonance wavelength of the micro cavity coincides with the third wavelength, the first organic light emission material layer is disposed at the position of the first antinode of the third wavelength and the second organic light emission material layer and the third organic light emission material layer are disposed at the position of the second antinode of the third wavelength resonating in the micro cavity.