Actuator assembly for electromechanical parking brake

PURPOSE: An actuator assembly unit for an electronic parking brake is provided to produce a high quality vehicle by significantly reducing vibration and noise of the actuator assembly unit of the electronic parking brake. CONSTITUTION: An actuator assembly unit for an electronic parking brake includes a first module and a final module (50). The first module comprises an inner housing (110), a motor (130), a reduction gear train, a planet gear set (170), and an inner cover (120). The final module accommodates the first module inside and is enclosed by an outer housing (210) and an outer cover (220).