A method of activating at least one electrical igniter incorporated in each of a plurality of gas generators provided in an air bag system is provided. The method includes: connecting an electronic control unit to a power source and an impact detecting sensor; providing a bus line having a plurality of loop wires passing through the electronic control unit to supply and transmit current and required information; connecting each of the at least one electrical igniter to the electronic control unit through the bus line branched from predetermined portions of the bus line; providing each of the at least one electrical igniter with a heat generating portion, a priming ignited by the heat generating portion, a capacitor, and an integrated circuit recorded with information to exhibit required functions; and supplying a current for igniting the priming to the at least one igniter through the capacitor.