An airbag device comprising: an airbag adapted to be expanded and inflated by admitting an inflating gas; and an inflator housed in the airbag for feeding the inflating gas to the inside of the airbag. The airbag includes an airbag body forming a bag-shaped outer peripheral wall, and a reinforcing cloth for preventing a gas leakage from the airbag body. The reinforcing cloth is joined at its peripheral edge on the upstream side of the inflating gas to the outer peripheral wall in the airbag body but is not joined at the edge portion of the reinforcing cloth on the downstream side of the inflating gas.