AIR BAG DEVICE

An airbag device in which the deployment behavior of a cushion is stable when expanded and deployed and the cushion does not tilt while restraining an occupant, even in a vehicle in which a console box is lower than the upper surface of a seat cushion or in a vehicle without a console box. The airbag device 1 includes a cushion 2 and an inflator 3 that injects gas to expand the cushion 2. The cushion 2 has a main chamber 2that expands and deploys on one side of the occupant, and a lower chamber 2that extends downward from a part of the main chamber 2. The lower chamber 2is formed so that, when expanded and deployed, a lower end part of the lower chamber 2can come into contact with the upper surface of a console box.