<p>A gas generator for an air bag and, in particular, an improvement in the housing of a gas generator. The invention aims at providing a light-weight gas generator of thin plate structure having a housing improved in strength, permitting filling of gas generating agent without the application of welding, and requiring advantageous manufacturing facilities. The gas generator is characterized by such a structure that: a combustion chamber is formed of a combustor cup (14) having an annular top surface whose inner periphery is fixed by rivetting (28) to the top wall peripheral edge of a central cylindrical holder (4); a combustor plate (16) is provided to be fixed by welding at the outer edge thereof to the inner peripheral edge of the outer flange (15) of said combustor cup (14) and also fixed to the opposite edge of said holder at the inner periphery; a diffuser (12) is provided to form a duplex wall by covering the top wall of said central holder (4) and the top surface of the combustor cup joined with said top wall; and the edge of the outer flange of said combustor cup is fixedly welded to the inner wall of the extended part of said diffuser. <IMAGE></p>
