An air bag cover is formed of synthetic resin and is connected to and held by the body of a car in a plurality of discontinuous portions thereof along the peripheral edge of an opening formed on the interior side of the car in such a manner that the air bag cover not only can cover an air bag folded in the peripheral edge of the opening on the car interior side, but also, when an air bag main body of the air bag is developed and expanded, can be so opened and moved as to allow the air bag main body to project toward the opening side. The air bag cover further includes a restricting wall which projects toward the body of the car in such a manner that it can connect together these connecting/holding portions while the restricting wall is disposed on the back surface side of the air bag cover, in more particular, on the side of the folded air bag main body that is distant from the opening and on the opening side of connecting/holding portions.