An air bag gas generating agent which can markedly reduce the concentration of toxic components, particularly both CO and NOx, in the aftergas, while maintaining various favorable properties of non-azide gas generating agents. The agent is of non-azide type and contains a nitrogen-containing organic compound and an oxidizing agent as the active ingredients and at least one metal oxide selected among molybdenum oxide, tungsten oxide, and metal oxides having a BET specific surface area of not less than 5 m /g as the combustion catalyst.