To provide an airbag device capable of simplifying the structure of folding an airbag.

There are provided an inflator 46 and an airbag 50 whose outer edges are joined to each other. The airbag 50 has a deflector built therein deflecting a gas from the inflator 46 into two mutually opposite directions oriented toward the outer edges while having a first outer edge located at a first direction to which the gas is deflected by the deflector, and a second outer edge located at a second direction which intersects the first direction orthogonally, and the first outer edge is wound up in the first direction while the second outer edge part is rolled in the second direction, and inwardly winds the outer surface of the inflator 46 side of the airbag 50.