A squib associated with a supplemental restraint system includes an igniting agent positioned above a first pin that is a connecting terminal providing a connection with a two-wire system bus wire, which is an external signal wire, and above a header that is provided with a second pin that is a connecting terminal. The squib also includes an IC substrate that controls communications and ignitions, and is positioned above the igniting agent, an ignition element between the igniting agent and the IC substrate, and joining portions provided in two locations bridging the igniting agent so as to connect the IC substrate with the first pin and the header. The IC substrate, the igniting agent, the pin, and the header are covered by a circular cylinder shaped cap whose top portion is closed off. Furthermore, these are formed integrally by being covered by a resin mold that is made to extend across the portions of the pins using a molding process. When the squib is operated it does not electrically affect the external signal wire.