A side airbag apparatus may include: a seat on which a passenger is seated; an inflator mounted on the seat, and configured to jet gas; a cushion inflated by the gas jetted from the inflator, and deployed toward the passenger so as to move the passenger to an inboard side of the vehicle; and a controller configured to operate the inflator to deploy the cushion before the collision of the vehicle, according to driving information of the vehicle, based on a signal of a sensor mounted on the vehicle.