An adjustment shaft actuator. The adjustment shaft actuator includes an adjustment shaft arranged parallel to a camshaft of a valve train and having a lever unit with a lever arm, a cam unit that has a cam and that is connected to the camshaft in a non-rotatable manner, whereby the lever unit is arranged so as to be axially movable on the adjustment shaft or the cam unit is arranged so as to be axially movable on the camshaft, and an adjustment unit provided in order to effectuate axial movement between the at least one lever unit and the at least one cam unit, by way of which the at least one lever arm can be brought into effective contact with the cam in order to bring about a rotation of the adjustment shaft by rotating the camshaft.