Abstract: A gas generation device for a vehicular passenger protecting system. The gas generation device is equipped with an auto ignition device that is ignitable at a predetermined temperature when the gas generator is heated from an external source. Thus a primary ignition agent having an ignition temperature lower than the ignition temperature of a secondary ignition agent ignites first, causing a pressure rise which in turn moves a sealing member. In one embodiment, the sealing member breaks a gas-tight container which causes the ignition of the secondary igniton agent, which in turn causes ignition of a gas generating agent. In a second embodiment, the sealing member causes ignition of the gas generating agent directly. In either case, the primary ignition agent ignites prior to sufficient loss in mechanical strength of the gas generation casing body housing the gas-tight container.