A display device capable of reducing afterimage, and an afterimage reduction method used by the display device. One or more afterimage reduction patterns having one or more opaque areas, and/or one or more semi-transparent areas and one or more non-opaque areas are stored in a storage unit. A composition unit outputs a final image composed of a displayed main image and afterimage reduction patterns output from the storage unit. A control unit causes afterimage reduction patterns selected by a user from the storage unit to be input to the composition unit, and a final image in which only pixels corresponding to opaque areas and/or semi-transparent areas in the main image are replaced by color of the opaque areas and/or semi-transparent areas in the afterimage reduction patterns to be output from the composition unit. Accordingly, it is possible to view a received main image while reducing afterimage using images of various patterns for afterimage reduction.