Seal for hinge for boot lid or rear door for motor vehicle

The device includes a reducer plug (40) fixed on an opening (27), and comprising a reduced passage (42) for a movable hinge (31). A rubber plug (50) is connected to the hinge such that it is applied with sealing to the reducer plug to close the reduced passage when a flap (30) is in closed position. The reducer plug is constituted of a rigid or semi-rigid plate.