Abstract: The invention relates to an actuator for the electromotive actuation of a parking or stop brake, especially of a private car. The actuator comprises, downstream on the electric motor, a planetary wheel transmission which is axially cascaded in a multi-stage manner and comprises a centering pin which is radially mounted on the two front ends thereof and extends coaxially to the output shaft, on the radial overdefined bearing arrangement thereof. Respectively one planet carrier comprising a pinion is embodied, along the centering pin, as a sun wheel for the planet wheels on the planet carrier of the following transmission step.