The present invention provides a current supplying circuit in which the weight of an air bag system is reduced.A current supplying circuit supplying a current required for actuating an electric igniter arranged in a gas generator at a time of actuation of the gas generator for an air bag, and comprising a switch circuit for opening or closing a current path for actuating the igniter, a pulse generator for providing a controlling pulse for opening or closing the switch circuit, and the switch circuit provided between the current path and an external power source, wherein.a current obtained from the external power source is supplied as an ignition pulse for actuating the igniter by the switch circuit, and the current is further adjusted such that the width of the ignition pulse is 20 to 500 .mu.sec to be supplied.