The invention pertains to a setting device for a ventilation flap(12, 12a, 12b) in an air duct, especially in a heating and ventilating unit of a motor vehicle, with an electric motor (2) to execute the setting movements and a control unit (3) for the electric motor (2). To keep down both the assembly cost and the number of replacement parts to be kept on hand, the invention provides that the electric motor (2) is designed as a stepping motor actuated by the output signals of a control unit (3) adjacent to this stepping motor and that the control unit (3) has coding inputs (K1, K2) for selecting the direction of rotation and/or the angle of rotation.