A display device comprising: a substrate; a switching element on the substrate; a pixel electrode disposed on the switching element and connected to the switching element; a light emitting layer on the pixel electrode; a common electrode on the light emitting layer; and a sealing portion on the common electrode, wherein the sealing portion comprises: an organic layer; and at least one first composite inorganic layer disposed between the organic layer and the common electrode, the at least one first composite inorganic layer comprises: a first inorganic layer between the common electrode and the organic layer; and a second inorganic layer between the first inorganic layer and the organic layer, and the first inorganic layer and the second inorganic layer have refractive indices different from each other, and the first inorganic layer and the second inorganic layer contact each other, and characterized in that the sealing portion comprises: a cover portion disposed on the common electrode, and an extension portion extending from the cover portion towards the substrate, wherein in a cross-sectional view the common electrode extends continuously below the cover portion and the extension portion, wherein the extension portion and the common electrode below the extension portion are inserted into the substrate, wherein a width of a first portion of the extension portion is greater than a width of a second portion of the extension portion, and the second portion is disposed closer to the cover portion than the first portion. a substrate; a switching element on the substrate; a pixel electrode disposed on the switching element and connected to the switching element; a light emitting layer on the pixel electrode; a common electrode on the light emitting layer; and a sealing portion on the common electrode, wherein the sealing portion comprises: an organic layer; and at least one first composite inorganic layer disposed between the organic layer and the common electrode, an organic layer; and at least one first composite inorganic layer disposed between the organic layer and the common electrode, the at least one first composite inorganic layer comprises: a first inorganic layer between the common electrode and the organic layer; and a second inorganic layer between the first inorganic layer and the organic layer, and a first inorganic layer between the common electrode and the organic layer; and a second inorganic layer between the first inorganic layer and the organic layer, and the first inorganic layer and the second inorganic layer have refractive indices different from each other, and the first inorganic layer and the second inorganic layer contact each other, and characterized in that the sealing portion comprises: a cover portion disposed on the common electrode, and an extension portion extending from the cover portion towards the substrate, a cover portion disposed on the common electrode, and an extension portion extending from the cover portion towards the substrate, wherein in a cross-sectional view the common electrode extends continuously below the cover portion and the extension portion, wherein the extension portion and the common electrode below the extension portion are inserted into the substrate, wherein a width of a first portion of the extension portion is greater than a width of a second portion of the extension portion, and the second portion is disposed closer to the cover portion than the first portion.