A vehicle occupant restraint device includes an airbag that is provided in a shoulder belt position of a seat belt while being folded in a belt-like shape to be capable of inflating upon receiving a predetermined actuating signal, and the seat belt is wound by a single winding device. The airbag is folded to surround a slide guide including a hard member having seat-belt passing portions arranged at predetermined intervals in an insertion direction of webbing and a soft member supporting the hard member. The airbag smoothly slides along the webbing through the slide guide when the seat belt is pulled out.