GAS GENERATOR

A cylinder-shaped gas generator (1A) includes an elongated and circular cylindrical housing, a working gas generation chamber and a filter chamber provided within the housing, and an igniter (30). The working gas generation chamber mainly contains a dividing member (50) and a granular gas generating agent (62). The dividing member (50) has a circular cylindrical portion (52), a bottom portion (53) and a hollow portion (55). The granular gas generating agent (62) is stored in the portion of the working gas generation chamber excluding the hollow portion (55). The bottom portion (53) of the dividing member (50) is configured to have a tapered shape such that its outer shape is reduced in size in accordance with a decrease in the distance from the igniter (30).