Abstract: In a side impact air bag system, a first vent hole and a second vent hole for reducing a pressure of a part opposing a chest portion of a passenger to a lower value than the pressure of a part opposing an abdomen portion of the passenger when the bag is inflated. The vent holes are provided on a side surface of an upper inflation unit opposite to the passenger, whereby regulating gas discharge of the part opposing the chest portion while preventing early discharge of the gas, always obtaining a desired internal pressure and inflation condition, positively inflating the bag and relaxing a shock to the chest portion.

Abstract: In a side impact air bag system, the blowing direction of gas is regulated by connecting a bag to an inflator through a gas intake portion which suppresses the diffusion of the gas. The bag is formed of a main body, a lower inflation unit, and an upper inflation unit having a vent hole. The upper inflation unit and the lower inflation unit are contained with the main body in a shape of bellows when installed. When the bag is inflated by a gas blown out from the inflator, the bag is inflated from a portion of the main body opposing an abdomen portion having a higher shock load resistance than that of a chest portion, thereby improving the restraining condition of a passenger by regulating the inflating condition of the bag into a desired condition. Consequently, a possibility of the bag being obstructed by vehicle structural members in the process of the bag inflated from inner sides of the upper inflation unit and the lower inflation unit is eliminated, thereby positively inflating the bag.