VEHICLE SIDE AIRBAG DEVICE

A vehicle side airbag device is stored inside a seatback of a vehicle seat and includes an airbag that inflates and deploys between a seated occupant and a side door. The interior of the airbag is partitioned into plural chambers including a high-pressure chamber, and the high-pressure chamber inflates and deploys so as to vertically straddle a door beltline as seen in vehicle lateral view and so as to restrain a shoulder region of the seated occupant.