An air bag device in which an internal acceleration sensor is prevented from operating a main body of an air bag device is mounted on a vehicle. The device is provided with a stopper for interlinking a fixing bolt for mounting the main body of the air bag device on the vehicle with a canceling screw for canceling the state of preventing the actuation of the acceleration sensor. Before the main body of the air bag device is threadingly inserted into the vehicle by means of the fixing screw and is thereby secure, the stopper keeps the canceling screw from being threadingly inserted.
