Abstract: A passive seat belt for an automobile is disclosed. A guide rail is mounted to a sashless door or a roof side rail, and a movable anchor member is adapted to move in the groove of the guide rail so that the one end of a belt, connected to the free end of the movable anchor member, may be kept at a certain height higher than the door panel for preventing the belt from contacting a part of a body of a driver or a passenger. The guide rail may be straight and positioned horizontally or may be bent at the rear end of the door. The movable anchor member may be locked by a locking stop. The guide rail is covered by a decorative trim piece. The movable anchor member is reinforced by a reinforcing member mounted to the door, the pillar, or the like of the automobile.