An air bag device includes a retainer having an opening, a lid for covering the opening of the retainer, an air bag accommodated in the retainer, at least one hinge member connecting the retainer and the lid, and at least one guide plate having a hook-shaped or J-shaped cross section to define a recess. The hinge member is bent at its mid portion along the recess of the guide plate, and one end portion of the hinge member is fixed to a reverse surface of the lid at one side thereof and the other end portion of the hinge member is fixed to the guide plate and sandwiched between the guide plate and the retainer.