The present invention provides a gas generator for a restraining device of a vehicle, including:a housing being made of a resin, forming an outer shell container, having a plurality of gas discharge ports,an ignition device disposed inside the housing,a gas generating agent that is ignited and burned by activation of the ignition device,each of the gas discharge ports being formed in combination with each of a plurality of through holes of an annular plate member that is embedded in a circumferential wall surface of the housing and formed of a material selected from the group consisting of metals, ceramics, and carbon fiber, andthe annular plate member being formed of an annular base plate including the plurality of through holes formed therein.