Provided is a side airbag device such that locally high stress is prevented from being generated at the sewn portion between panels by high temperature and pressure gas. An inner panel is folded in half, and the upper edges thereof are sewn together by a seam so as to form an inner bag. This inner bag is placed on an outer panel, the outer panel is folded in half, and the periphery thereof is sewn by a seam. An inflator equipped with a distributor is inserted into the inner bag through openings and, and a gas jetting portion is disposed in the immediate vicinity of a communication opening.