To solve the tendency to a reversing device to cause a packing phenomenon by the flow against anti-thrust flow and the tendency to reduce the efficiency of the reversing device by the action of the dynamic pressure of air by the motion of an aircraft.

A main gate 7 which is integrated into the wall of a nacelle, in direct jet operation, in the closed position and can form the deflecting barrier of a reversing current 11a in the expanded position is connected to an auxiliary gate 10 which is integrated into the wall of the nacelle in direct jet, and can expand in the upstream of a reversing sink 24b so as to form a barrier to an external flow 14 flowing on the outer surface of the wall of the nacelle in thrust reversion and form a duct line for the reversing current.