A method of manufacturing a display device includes attaching a protective film onto a display panel that includes a display area and a pad area, where the protective film includes an adhesive layer and a protective layer disposed on the adhesive layer, half-cutting the protective film along a cutting line between the display area and the pad area such that a total thickness of the protective layer and a partial thickness of the adhesive layer are cut, irradiating a partially cut portion of the adhesive layer with a laser beam along at least a portion of the cutting line, and detaching a portion of the protective film that corresponds to the pad area along the cutting line.