An inflator includes in a combustion chamber a first gas generating charge and a second gas generating charge to be ignited and burned to generate an inflation gas. The second gas generating charge is slower in speed of combustion than the first gas generating charge. The inflator further includes a partition wall that segregates the first and second gas generating charges. The partition wall is located away from an ignition area of an ignition device that ignites the first gas generating charge, with the first gas generating charge located between itself and the ignition area. The partition wall is burnable to destruction by the fire generated by combustion of the first gas generating charge so as to permit propagation of the fire to the second gas generating charge by its generally entire area.