A passenger retention-belt system is intended for use with a seat which is arranged in a vehicle. The system has a seat belt for retaining a passenger on the seat in a first retention position. The seat belt is driven by a first and a second preloading mechanism. The first preloading mechanism works in such a manner that it draws the seat belt from the first retention position into a second retention position, in which a first degree of tension is exerted on the seat belt in order thus to retain the passenger on the seat, while operation processes of the passenger are possible in order to avoid a vehicle collision when vehicle collision is feared. The second preloading mechanism works in such a manner that it draws the seat belt from the second retention position back into a third retention position, in which a second, greater extent of tension is exerted on the seat belt in order thus to retain the passenger on the seat against impacts which are caused by a vehicle collision when the vehicle collision is detected.
