The present invention relates to a micro motor including a hub, a rib structure, an inner ring, an outer ring and at least two micro actuators, in which a top edge of the hub is projected outwardly to form a top lid, a plurality of bumps are provided between the rib structure and the top lid, and protruded limiting parts are disposed between the wall of the inner hole of the rib structure and the outer periphery of the hub so that the rib structure is in point contact with the hub and the top lid. Therefore, when the micro actuators drive the rib structure, the inner ring and the outer ring to rotate, mutual abrasion among those parts can be reduced to prolong the lifespan of the micro motor.