SIDE AIRBAG DEVICE

The side airbag device includes an inflator and a side airbag that is stored in a folded state in a side portion of a seatback of a vehicle seat and is inflatable and deployable in a space between a vehicle sidewall and a side portion of an occupant. The side airbag includes an outer bag and an inner bag. The inner bag houses the inflator and is disposed at a rear portion of the outer bag along an extending direction of the seatback. The outer bag is provided with a vent hole configured to communicate with an outside. The inner bag is provided with a gas circulating hole configured to communicate with the outer bag. The gas circulating hole is disposed at a position to be blocked by the outer bag when the side airbag in an inflated and deployed state is pressed between the occupant and the vehicle sidewall.