Abstract: The invention concerns a protective device comprising an airbag worn by a person, a pyrotechnic gas generator for inflating the airbag, and an actuator for the gas generator. The invention is such that the gas generator has a dual state combustion. Preferably, the generator is single-piece with single ignition. The invention device enables to provide a first inflating phase lasting about 60 ms at most, preferably between 30 and 50 ms; then a second phase maintaining inflation lasting at least a few seconds, preferably at least 4 s, more preferably still between 5 and 8 s.