An air bag system includes an air bag which can cover a front surface side of a front pillar of a vehicle. The air bag includes an inflatable main body portion and a supporting inflatable portion. The inflatable main body portion covers a front surface of the front pillar when the air bag is inflated completely. The supporting inflatable portion stretches continuously from the inflation main body portion so as to extend towards an outside of the vehicle from the inflation main body portion and is disposed to be brought into abutment with an upper surface of a mirror main body of a door mirror which is in a usable position on a lower surface side so as to be supported thereon to thereby support the inflatable main body portion, when the air bag is inflated completely.