An optical actuator includes a base, a light-transmitting plate, a frame, a plurality of suspension members, and a plurality of actuation members. The base has a mounting surface. The light-transmitting plate is located above the mounting surface. The frame frames an outer edge of the light-transmitting plate. The frame retreats inwardly relative to the mounting surface, so that the mounting surface has a plurality of disposing areas relative to the frame. The suspension members are respectively located on the disposing areas and connected between the base and the frame. The actuation members are respectively located on the disposing area and configured to drive the frame to reciprocate relative to the mounting surface.