Abstract: A stereoscopic image display including an image displaying unit and a directional light modulator is provided. The image displaying unit has a black matrix. The directional light modulator is disposed corresponding to the image displaying unit, wherein the directional light modulator comprises a plurality of constitutional groups repeating arranged in a first direction. Each of constitutional groups comprises a plurality of periodically changed structures, and each periodically changed structure in same constitutional group changes its size along the first direction.