A device for manoeuvring an aerodynamic flap (1) arranged on a motor vehicle, characterised in that it comprises mechanical means for shifting the flap from a retracted position to a deployed position, successively performing a movement extending the flap while keeping the plane of the flap parallel to the direction of an air stream flowing around the flap when the vehicle is moving, such that the aerodynamic pressure exerted on the flap is substantially zero, and then a movement pivoting the flap about a pivot axis (AA') located in a plane of the flap and passing substantially through a centre of aerodynamic thrust (10) of the flap, such that the torque applied to the pivot axis (AA') and resulting from the aerodynamic forces is substantially zero. The shift from a deployed position to a retracted position is carried out by performing said movements in reverse order.