GAS GENERATOR

The present invention provides a gas generator, including: a cylindrical housing; an ignition device installed at a first end of the cylindrical housing, and a diffuser portion installed at a second end thereof; a flow channel forming member disposed inside the cylindrical housing and including a partition wall which separates a first chamber from a second chamber; a combustion chamber formed in the first chamber; a discharge passage formed in the second chamber; a first cylindrical space formed on the outside of the first circumferential wall and a first communication hole formed in the first circumferential wall; a second cylindrical space formed on the outside of the second circumferential wall and being in communication with the first cylindrical space, and a second communication hole formed in the second circumferential wall; a cylindrical filter disposed in the second cylindrical space; an outer diameter (d) of the first circumferential wall, an outer diameter (d) of the second circumferential wall and an outer diameter (d) of the cylindrical filter satisfying relationships of d>d and d≥d; and between the cylindrical filter and the inner wall surface of the cylindrical housing, the second cylindrical space facing the second communication hole via the cylindrical filter.