Side airbag apparatus

An airbag includes a pair of fabric main portions , which are laid on top of each other in the width direction of a vehicle. The fabric main portions are joined to each other at the periphery. An inflator incorporated in the airbag jets inflation gas G through gas outlet , thereby inflating and deploying the airbag forward in a space between an occupant P and a body side portion. A third reinforcing fabric sheet includes a reinforcing fabric portions . The reinforcing fabric portions extend to a position forward of a center portion C of the fabric main portions in a front-rear direction from the rear ends of the fabric main portions , which are located outside of the reinforcing fabric portions . The front ends of the reinforcing fabric portions are joined (sewn) to the fabric main portions by front joint portions . The outer reinforcing fabric portion has a hole in a part between a rear end R and the front joint portion