When an air bag is prepared by laying a pair of silicone rubber-impregnated and/or coated base fabric pieces one on the other, with the coated surfaces of the pieces inside, and joining peripheral portions of the pieces together to form a bag, an addition reaction curing type silicone rubber composition which cures into a silicone rubber having an elongation at break of at least 1000% is used as a sealer and applied to the peripheral portions of the base fabric pieces, thereby achieving improved adhesion therebetween.