SIDE AIRBAG DEVICE

A side airbag device having an airbag cushion that restrains an occupant by expanding and deploying and an inflator disposed on an inner side of the seat frame that supplies expansion gas to the airbag cushion; and a holding part that holds the airbag cushion. The airbag cushion includes an inner expanding portion internally containing the inflator and an outer expanding portion connected to the inner expanding portion and is disposed on an outer side of the seat frame by being folded back at a front edge portion of the seat frame. The outer expanding portion includes a folded portion of the airbag cushion. A forward portion of the holding part contacts an outer surface of the folded portion of the outer expanding portion, and a rearward portion is connected to the seat frame. Furthermore, the holding part is configured to cover a part of the outer expanding portion.