An airbag device includes an airbag, first and second inflators, a gas-supply mechanism and a release member for connecting between a holding structure and the airbag. Gas generated by the second inflator is supplied into the airbag when the release member is pulled by the airbag while gas generated by the first inflator inflates the airbag. According to the airbag device, a gas amount supplied into an airbag can be switched according to an occupant's seating position without equipping a sensor for measuring a distance between an occupant and the airbag or a control device for computing the gas amount supplied.