<p>A planetary gear mechanism having a common axis is constituted separately of a gear mechanism for transmitting a driving force from an electric motor (3) to an output gear (12) to move an output screw shaft (4). This planetary gear mechanism is decelerated to bring the planetary gear into meshing engagement, and a pointer lever (27) is connected so that it may act integrally with a carrier (22) acting as the member of the final stage, to which the rotating torque is transmitted.</p>
