There is provided an airbag device being excellent in performance of protection of an occupant wherein a folded airbag (10) undergoes sequential and orderly expansion starting from a region where the expansion ought to be started. It is characterized in that a gas rectification member (12′) for rectifying and guiding a gas generated from an inflator (30) up to the vicinity of a part of the airbag (10), inflating in the initial stage of the expansion thereof, is provided substantially at the central part of the airbag (10).