Disclosed is a step actuator. The step actuator includes a housing; a stator installed in the housing; a rotor positioned radially inward from the stator, the rotor rotating and protruding from one side of the housing; a bearing installed at one side of the housing so as to be coupled with the rotor; a bearing cover coupled with one side of the housing to restrain movement of the bearing; a screw member coupled with the rotor to linearly move according to rotation of the rotor; and a mounting member coupled to the bearing cover to support the screw member.