The invention provides a display device and a manufacturing method thereof. The display device includes a substrate including a plurality of pixel areas, a thin film transistor positioned on the substrate, a first insulating layer positioned on the thin film transistor, a pixel electrode connected with the thin film transistor and positioned on the first insulating layer, a common electrode positioned on the pixel electrode and spaced apart from the pixel electrode by a microcavity, a second insulating layer positioned on the common electrode, a roof layer positioned on the second insulating layer, a thickness of the roof layer being about 4 [mu]m to about 50 [mu]m, an injection hole through the common electrode, the second insulating layer, and the roof layer, the injection hole exposing a part of the microcavity, a liquid crystal layer filling the microcavity, and an overcoat on the roof layer and extending into the injection hole, the overcoat sealing the microcavity.