SIDE AIR BAG APPARATUS FOR VEHICLE

A side air bag apparatus for a vehicle. The side air bag apparatus includes: a first cushion configured to cover and protect an upper body area of a passenger who has adopted a relax mode while tilting rearward a seatback; a second cushion configured to cover and protect a head area; and a valve member configured to open and close a vent hole connecting the first cushion to the second cushion. Accordingly, both the upper body area and the head area of the passenger in the relax mode are efficiently and sufficiently protected.