To provide a protective device provided with a discharging device expanding an expandable body without loss of gas so that the discharging device and a protective body optimize an expansion of the expandable body and guaranteeing progressive discharge of the gas at the moment a collision occurs.

This discharging device discharges the expandable body 1 for protecting a vehicle 5 against a collision. Once the expandable body 1 expands, it takes on a normal form covering and closely fitting an area to be protected of the vehicle 5. The expandable body 1 is held inside a compartment 2 in a folded state, and the discharging device includes an opening having an end part 1b connected to a wall part 2a of the compartment 2 so as to seal it. It is characterized by that the wall part 2a facing the opening includes an outgassing means 7 protected during the expansion of the expandable body 1 by a closing flap 9 controlled by an actuator means 10 moving the closing flap 9 when the expandable body 1 is expanded.