AIRBAG

An airbag mounted on a steering wheel including a grip portion gripped by an occupant and a boss portion connected to a steering shaft of a vehicle, the airbag being inflated by being supplied with an inflation gas, and covering an entire area of the grip portion from behind when the airbag is completely inflated, the airbag that is completely inflated including: an occupant-side panel disposed on a rear side and configured to receive the occupant; a steering wheel-side panel disposed on a front side and supported in contact with the grip portion; and a side panel sewn to the occupant-side panel and the steering wheel-side panel and connecting the occupant-side panel and the steering wheel-side panel, in which a width of the side panel in a front-rear direction along a rotation axis of the steering shaft is larger than a width of the occupant-side panel in a left-right direction.