A side airbag system has a side airbag unit, a posture detector, a weight
detector, and a deployment controller. The side airbag unit includes an
airbag to be deployed with respect to the sideward direction of the
occupant sitting on a vehicle seat. The posture detector determines the
posture of the occupant. The weight detector measures the weight of the
occupant. The deployment controller controls the deployment of the airbag
based on the posture checked by the posture detector and weight measured
by the weight detector of the occupant.