Abstract: A side airbag device stowed in a side part of a vehicle seat and includes: an airbag for restraining an occupant by expanding and deploying; and an inflator provided in a side wall part of a seat frame in the vehicle width direction extending in the vehicle traveling direction when a horizontal cross section of the vehicle seat is viewed from above, and that supplies expansion gas to the airbag. The airbag includes a main chamber that expands and deploys towards the front and a pre-push chamber that expands and deploys before the main chamber to the inside of the main chamber in the vehicle width direction. Furthermore, the pre-push chamber has a structure with an extension portion extending from the inflator towards the rear of the vehicle seat.

Abstract: The side airbag device is provided with a cushion, an inflator arranged on the occupant side of a side part of a seat frame, and a support plate, where the cushion in a folded state includes: a first portion positioned on the occupant side of the seat frame side part, and a second portion positioned on the side opposite the occupant side of the seat frame side part and wraps around the vehicle front side from the first portion to sandwich the seat frame side part together with the first portion; and the support plate includes: a main body part for supporting the second portion, and a rearward extending part, in which through-holes and are formed extending from the main body part toward the rear of the vehicle beyond the second portion for allowing stud bolts and of the inflator to pass through.

Abstract: 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.