INFLATOR

The present invention provides an inflator in which a flow amount of a pressurized gas can be kept almost constant. Fragments produced by rupture of a first rupturable plate 22 are arrested around a top 20b of an inner surface of a filter 20, and the remaining portion of the inner surface does not contact with fragments. Therefore, since a gas flow does is not blocked by the fragments, a flow amount of a pressurized gas can be kept almost constant.