A seat belt is a vehicle safety device designed to secure the occupant of a vehicle against harmful movement that may result during a collision or a sudden stop. In recent years, serious and fatal accidents have decreased in number. The reason is that more and more people begin to understand the importance of using safety belts. When driver makes a sudden stop, the speed from the car causes driver to hit the seat belt with significant force. That force saves life, but can leave passenger with bruises, scrapes and fractures. In this paper the influence of different force values on the abdomen of the driver by the seat belt is analyzed. As a result, the different speed values of the car, due to sudden braking, give different values of force which the seat belt acts on the driver.