The operation efficiency is improved by enabling a gas rectifying member of an airbag device to be easily disposed in a folded airbag. An airbag in a folded state is accommodated around an inflator of an airbag device, and a gas rectifying member (12) for guiding gas is disposed between the airbag and the inflator surrounded by the airbag. The gas rectifying member (12) includes a retained portion (12A) retained, together with the airbag, around the inflator and a free-standing tubular gas-flow guide portion (12B) standing upright from the retained portion (12A), which are formed as a single part from a base fabric. The airbag is folded in a state in which the retained portion (12A) is retained inside the airbag. At this time, the gas-flow guide portion (12B) is less likely to be sandwiched between the airbag, because it is standing in the airbag.