bag main body the strap 3 is firmly ejected from the gap between the inner panel 11 b of the front pillar 11 and the pillar trim 14 therefore a situation in which the strap 3 is caught by the pillar trim 14 in developing to expand the air bag main body 2 can be avoided and the air bag main body 2 can be developed ideally or as designed further although the gap between the inner panel 11 b and the pillar trim 14 is closed by the tongue piece 16 a of the weather strip 16 since the tongue piece 16 a is formed by an elastic body the strap 3 can be ejected in developing the air bag main body 2 while achieving promotion of the outlook when the air bag main body 2 is not operated particularly by arranging the slip 17 at the portions of the pillar trim 14 and head lining 200 overlapping each other at an initial stage of pulling out the strap 3 the strap 3 can firmly be pulled out from the gap further thereafter the strap 3 is ejected successively from the gap and therefore the situation in which the strap 3 is caught by the pillar trim 14 can firmly be eliminated further.