Abstract: A passive seat belt device for a motor-vehicle occupant has at least a shoulder belt which is secured at its one end to the inner, side upper wall portion of a compartment of the vehicle and used for binding the breast portion of the occupant. A drive mechanism is provided for automatically bringing the seat belt in tightening and releasing positions for the occupant in response to the opening and closing operations of a door of the vehicle. A support secured to the inner, side wall portion of said compartment on the side of said secured one end of said shoulder belt guides the shoulder belt in a manner to keep the shoulder belt apart from the neck portion of said occupant.