A gas generator including a housing, a combustion chamber formed in the housing, the combustion chamber being packed with gas generant to generate high temperature gas by burning and also having a filtering member, an igniter device, secured in the housing, for igniting and burning the gas generant packed in the combustion chamber, and a gas discharge hole, formed in the housing, to communicate between an interior of the housing and an exterior of the same through the combustion chamber and a gas flow pass, wherein a coolant is arranged in the gas flow pass.