A gas generator (S) comprising a long-sized cylindrical housing (1), within which a combustion chamber (3), a cylindrical filter member (2) and a gas passage chamber (4) are arranged in series in the order mentioned. The combustion chamber (3) has a gas generating agent (5) filled therein and the gas passage chamber (4) has a plurality of gas discharge holes (7a) formed therein to communicate with an air bag. The housing (1) has an ignition means (6) installed therein to ignite and burn the gas generating agent (5) in the combustion chamber (3).
