A rotation stop shape is visually recognizable through an exposing hole. A relative angle between an output shaft and an actuator lever can be freely set while the rotation stop shape, which is visually recognizable through the exposing hole, is used as the reference angle of the output shaft. Therefore, it is possible to limit disadvantageous variations in a fixation angle of the actuator lever. The fixation angle of the actuator lever relative to the output shaft can be freely changed by using the rotation stop shape, which is visually recognizable through the exposing hole, as a reference angle of the output shaft.