An air bag is formed by joining together the outer peripheral edges of a pair of bag cloths substantially identical in the outer shape with each other. One of the pair of bag cloths constitutes an occupant side surface which, when the air bag is deployed, is located on the occupant side, while the other constitutes a vehicle body side surface which, when the air bag is deployed, is located on the vehicle body side. In the interior of the air bag, there are disposed drawing strips which pull in the outer peripheral edges of the occupant side surface and vehicle body side surface to the vicinity of the central portion of the air bag when the air bag is deployed.