An apparatus for manufacturing a display device and a method of manufacturing a display device is disclosed. In one aspect, the apparatus includes a guider configured to guide a substrate on which a display portion is formed, a plasma sprayer configured to be spaced apart from the display portion and configured to spray plasma onto the substrate and a mask configured to be arranged over the substrate and cover the display portion. The mask includes a body portion configured to face the display portion and a protrusion portion formed at an end of the body portion and configured to extend towards the substrate.