A micro actuator is provided to increase a resonant frequency by reducing the total weight of a movable plate and to maintain intensity of the movable plate. A micro actuator includes a base frame(110) and a movable plate(120). Both ends of the movable plate are supported in the base frame by a plurality of elastic supports(1231,1232). A reflective mirror is formed in one side of the movable plate. The reflective mirror changes an optical path. At least one first rib(124) is formed in an edge of other side of the movable plate with a closed curve. A second rib(126) is formed in the center of the other side of the movable plate. A permanent magnet(127) is positioned inside of the second rib. The remaining part of the other side of the movable plate except for the first and second ribs is removed with a predetermined depth.
