A device for measuring tensile stress acting on a vehicle seat belt has two components. A first component is connected with a seat belt and a second component is fixed to a vehicle part a spring arranged between the two components, against whose force the two components may be moved relative to one another. A transducer has transducer elements that are attached to the two components and produces an electrical signal as a function of the positions of the two components relative to one another. The transducer produces a switching signal when the components are in a first positional zone. In a second positional zone, in which the two components may be moved relative to one another against the force of the spring, the transducer produces measuring signals proportional to the movement of the two components relative to one another.