A display device comprising: a light source which emits a first light (B, B'); a color filter comprising a plurality of quantum dots which absorbs the first light (B, B') and emits at least one of a second light (G, G') and a third light (R, R'), wherein the second light (G, G') and the third light (R, R') are of a different wavelength to the first light (B, B'); a first optical filter layer disposed on the color filter, wherein the first optical filter functions as a long-wave band-pass filter blocking at least a part of the first light (B, B'); and a second optical filter layer disposed between the light source and the color filter, wherein the second optical filter functions as a short-wave band-pass filter transmitting at least a part of the first light (B, B') and reflecting at least a part of the second light (G') and the third light (R'), wherein the first optical filter layer, the color filter and the second optical filter layer are sequentially stacked, the first optical filter layer functions as a semi-transmission layer, the first optical filter layer emits light of at least one of the second (G, G') and third light (R, R') around a wavelength corresponding to the resonance wavelength of a microcavity formed of the assembly of the first optical filter layer, the color filter and the second optical filter layer, and the second optical filter layer functions as a reflection layer so that light of at least one of the second (G, G') and third light (R, R'), except for a directly emitted part of the light of at least one of the second and third light around a wavelength corresponding to the resonance wavelength of the microcavity, goes back and forth between the first optical filter layer and the second optical filter layer, and wherein the first optical filter layer and the second optical filter layer are spaced apart from each other with a distance determined based on an optical length of the at least one second and third lights (G,G', R, R') between the first and second optical filter layers (30, 40) and corresponding to the resonance wavelength of the microcavity for at least one of the second and third lights (G, G', R, R'). a light source which emits a first light (B, B'); a color filter comprising a plurality of quantum dots which absorbs the first light (B, B') and emits at least one of a second light (G, G') and a third light (R, R'), wherein the second light (G, G') and the third light (R, R') are of a different wavelength to the first light (B, B'); a first optical filter layer disposed on the color filter, wherein the first optical filter functions as a long-wave band-pass filter blocking at least a part of the first light (B, B'); and a second optical filter layer disposed between the light source and the color filter, wherein the second optical filter functions as a short-wave band-pass filter transmitting at least a part of the first light (B, B') and reflecting at least a part of the second light (G') and the third light (R'), wherein the first optical filter layer, the color filter and the second optical filter layer are sequentially stacked, the first optical filter layer functions as a semi-transmission layer, the first optical filter layer emits light of at least one of the second (G, G') and third light (R, R') around a wavelength corresponding to the resonance wavelength of a microcavity formed of the assembly of the first optical filter layer, the color filter and the second optical filter layer, and the second optical filter layer functions as a reflection layer so that light of at least one of the second (G, G') and third light (R, R'), except for a directly emitted part of the light of at least one of the second and third light around a wavelength corresponding to the resonance wavelength of the microcavity, goes back and forth between the first optical filter layer and the second optical filter layer, and wherein the first optical filter layer and the second optical filter layer are spaced apart from each other with a distance determined based on an optical length of the at least one second and third lights (G,G', R, R') between the first and second optical filter layers (30, 40) and corresponding to the resonance wavelength of the microcavity for at least one of the second and third lights (G, G', R, R').