An airbag device capable of reducing the volume of an airbag while still securing occupant restraining capability. The occupant seat airbag device (10) is disposed inside a vehicle front-rear direction curved section (15B) of an instrument panel (15) facing both towards the vehicle top-bottom direction top side and vehicle front-rear direction rear side. The airbag (20) is configured including a pair of outer deployment sections (26) that receive gas supplied from an inflator (22) and inflate and deploy separately from each other in the vehicle width direction, and an inner deployment section (28) formed by a connecting a cloth (34) around substantially the entire periphery of the outer edges of the pair of outer deployment sections (26). An occupant side deployment section (28P) of the inner deployment section (28) does not receive gas supplied from the inflator (22) and deploys as the pair of outer deployment sections (26) deploy.