A display device includes: a substrate including a display area and a non-display area; a circuit portion including a first circuit portion and a second circuit portion on the non-display area; a valley portion separating the first circuit portion and the second circuit portion from each other; and a thin film encapsulation layer sealing the display area, the thin film encapsulation layer extending from the display area to the valley portion, and the first circuit portion is between the valley portion and the display area, the second circuit portion is at an outside of the valley portion, an internal layer on the first circuit portion includes a plurality of island portions that are apart from one another in a first direction and a second direction crossing the first direction, and an external layer on the second circuit portion includes at least one groove extending in the first direction.