An airbag device includes an airbag configured to deploy in front of a front pillar of a vehicle; an inflator configured to supply expansion gas to expand the airbag; and a gas tube provided in the airbag and configured to supply the expansion gas from the inflator. The front pillar includes a storage formed inside the front pillar in a vehicle compartment and configured to store at least the airbag, and a partition configured to separate between an inside and an outside of the vehicle component. A partition hole is open in the partition. Before the expansion gas is supplied from the inflator, part of the airbag and an injection port configured to inject the expansion gas from the gas tube are disposed in front of or in the partition hole, and the injection port is disposed facing the outside of the vehicle compartment.