An example optical system for a 3D stereoscopic image display comprises a changing mirror, a rotating mirror, a tilted mirror, a concave mirror and a planar mirror. The changing mirror can change the path of light from a horizontal direction to a vertical direction. The rotating mirror can rotate while having an X-axis and a Y-axis with different curvature radii. The tilted mirror can include a central region with a hole for allowing light to pass therethrough, and a peripheral region having one surface having a concave tilted structure while the other surface has a planar structure. The concave mirror can include a central region with a hole having a size capable of encompassing the tilted mirror and a peripheral region having a bent structure that is completely concave. The planar mirror can include a central region with a hole and a peripheral region with a flat doughnut structure.