A display device comprising: a first substrate comprising at least one light-emitting element (ED1, ED2, ED3); a second substrate facing the first substrate, wherein light emitted from the light-emitting element (ED1, ED2, ED3) is to be incident on the second substrate; and a filling layer between the first substrate and the second substrate, wherein the filling layer comprises a filling pattern comprising a first pattern part on the first substrate and a second pattern part on the first pattern part, wherein there is an interface between the first pattern part and the second pattern part, the interface between the first pattern part and the second pattern part having, in a vertical cross-sectional view of the display device, a curve portion in at least a part thereof, and wherein the curve portion has at least one convex portion protruding upwardly from a straight line extending from one end of the curve portion toward an opposite end thereof, and at least one concave portion protruding downwardly from the straight line, and the light emitted from the light-emitting element (ED1, ED2, ED3) is to be incident on the filling pattern, characterized in that the second pattern part comprises substantially the same material as the first pattern part, at least a part of the filling pattern overlaps with the light-emitting element (ED1, ED2, ED3), and the filling pattern comprises cells (511, 512, 513), and the cells (511, 512, 513) of the filling pattern are spaced apart from one another, and wherein the filling layer further comprises a filling material between the cells (511, 512, 513) of the filling pattern, wherein a refractive index of the filling material is smaller than a refractive index of the filling pattern a first substrate comprising at least one light-emitting element (ED1, ED2, ED3); a second substrate facing the first substrate, wherein light emitted from the light-emitting element (ED1, ED2, ED3) is to be incident on the second substrate; and a filling layer between the first substrate and the second substrate, wherein the filling layer comprises a filling pattern comprising a first pattern part on the first substrate and a second pattern part on the first pattern part, wherein there is an interface between the first pattern part and the second pattern part, the interface between the first pattern part and the second pattern part having, in a vertical cross-sectional view of the display device, a curve portion in at least a part thereof, and wherein the curve portion has at least one convex portion protruding upwardly from a straight line extending from one end of the curve portion toward an opposite end thereof, and at least one concave portion protruding downwardly from the straight line, and the light emitted from the light-emitting element (ED1, ED2, ED3) is to be incident on the filling pattern, characterized in that the second pattern part comprises substantially the same material as the first pattern part, at least a part of the filling pattern overlaps with the light-emitting element (ED1, ED2, ED3), and the filling pattern comprises cells (511, 512, 513), and the cells (511, 512, 513) of the filling pattern are spaced apart from one another, and wherein the filling layer further comprises a filling material between the cells (511, 512, 513) of the filling pattern, wherein a refractive index of the filling material is smaller than a refractive index of the filling pattern