An aerodynamic element includes at least one first, fixed aerodynamic part including a box section that is covered at least partly by a plate with an extreme part, and one second aerodynamic part including a peripheral surface with an end and at least one holding element provided with a shoulder which forms, with the extreme part of the plate, a groove in which the end of the peripheral surface can be housed, such that the peripheral surface and the plate form a junction having an ascending profile. The presence of the groove makes it possible to obtain a continuous ascending junction with favors a laminar airstream on the upper surface of the aerodynamic element.