Airbag gas generator

The invention relates to an airbag gas generator having a housing (3) with discharge ports (11). Said housing comprises a combustion chamber (28) for a gas generating agent (6) and ignition means (4,5) for igniting and burning the gas generating agent (6) to generate a combustion gas which is to be discharged through the discharge ports (11). The combustion volume of the combustion chamber (28) is expandable.