To provide a speedometer of a vehicle for preventing a seat belt from being not attached by rendering the structure incapable of regular running on a road by a vehicle without surely attaching a seat belt, but capable of starting, traveling and garaging without installing the seat belt in the parking lot, factory and ground-plot.

There is provided a safe mode providing the speedometer and the seat belt, rendering the structure of the speedometer capable of starting, traveling without setting the seat belt, controlling the speed within a dozen kilometers per hour, but incapable of speeding up by even applying a accelerator, and capable of driving safely due to low speed notwithstanding an indicating panel of the speedometer is blurry. A seat belt lock fitting detection switch for detecting the setting of the seat belt is provided, and the lock fitting detection switch, the safe mode is which the indication panel of the speedometer of the vehicle is blurry, and the accelerator are provided to interlock. By setting the seat belt the vehicle can make regular driving and the indication panel of the vehicle becomes a clear and regular mode.