A far side airbag device includes: a side airbag that is configured to receive a gas supply and, while being supported at a seatback of a seat, expand and inflate at a vehicle width direction middle side relative to a range at least from the chest to the head of an occupant of the seat; and a limiting structure that limits a thickness in the vehicle width direction of the side airbag in an inflated and expanded state such that a region that inflates and expands at the vehicle width direction middle side relative to the head of a small occupant is thinner than a region that inflates and expands at the vehicle width direction middle side relative to the head of a large occupant.