A squib includes a cup body and a closure plug for holding a plurality of electrode pins insulated from one another and closing the opening of the cup body, and further includes, in the cup body, ignition powder and an ASIC component formed by molding a resin around electric circuits including an ASIC and a capacitor, a heating element connected to the ASIC and located at the top of the resin molding of the ASIC component, and connection electrodes located at the bottom of the resin molding for connecting the ASIC to the electrode pins. The squib includes a cylindrical metal fixture having at the center of its top an opening of a size sufficient to expose the heating element and being fixed to the closure plug in a state covering the top circumferential periphery and side surface of the ASIC component and pushing the connection electrode of the ASIC component against the electrode pins. With the squib thus constructed, electric current can be reliably supplied to the electric circuits incorporated in the squib, and upon operation of the squib the resin molding and its broken pieces are effectively prevented from flying in all directions.