Patent ID: 7658402

Claim:
An airbag for a curtain airbag system that is disposed over substantially the entire length of a roof side rail of a vehicle in the front and rear directions and stored on the roof side rail in the folded state, and being expandingly deployable with gas sent from an inflator which is introduced through a gas introduction hole of the airbag, the airbag comprising a duct formed with the gas introduction hole and a plurality of chambers communicating with the duct, the duct including a first duct part and a second duct part which is shorter than the first duct part, and the gas introduction hole being arranged between the first and second duct parts, wherein an inlet, which is closest to the gas introduction hole in the first duct part and is for one of the chambers, has a shape that becomes narrower gradually from an upper part toward a lower part, and a passage width of an uppermost part of the inlet of the closest chamber is greater than a depth to a narrowest part of the inlet of the closest chamber, and a passage width of the narrowest part is narrower than a passage width of the first duct part around the inlet of the closest chamber.