The invention relates to a regulating device for an actuator arranged in a gas passageway of an internal combustion engine, in particular for a bypass flap arranged in an exhaust turbocharger, having an electrical servomotor, a regulating member coupled to the actuator and a multi-gear transmission arranged between the servomotor and regulating member. According to the invention, to achieve a large transmission ratio range with a small number of transmission gears, two transmission wheels interact in at least one of the transmission gears via an evoloid toothing.