SIDE AIRBAG DEVICE AND VEHICLE

A side airbag device is provided between a body and a seat of a vehicle. The side airbag device includes an airbag module, a base member, and a retainer member. The base member is disposed between the body and the seat, and includes an airbag housing portion in which the airbag module is contained. The retainer member is a member that supports the airbag housing portion. The retainer member includes a retainer body and a retainer attaching portion extending downward from the retainer body. The base member includes a base member body in which the airbag storage is provided, and a cover extending from the base member body. The retainer attaching portion includes a fastening portion that fastens the retainer member to the body or a frame of the seat. The cover extends at least to a position where the fastening portion is disposed and covers the retainer attaching portion.