PURPOSE: To prevent the generation of an error or a mistake in the measure ment of speeding, by providing a speed measuring apparatus between a vehicle to be measured and a measuring vehicle and an earth speed measuring apparatus provided with the measuring speed, etc.

CONSTITUTION: A speed measuring apparatus between a vehicle to be measured and a measuring vehicle and an earth speed measuring apparatus provided with the measuring apparatus are provided. Further, an information operation apparatus for operating information from the speed measuring apparatus and the earth speed measuring apparatus is provided. Then, measurement is performed in such a state that the distance between vehicles is not kept constant by visual measurement but speed difference is held to zero by the earth speed measuring apparatus or the difference between the ground speed of the measur ing vehicle and the speed thereof to the vehicle to be measured is calculated. At this time, if the speed to the vehicle is positive, said speed is subtracted from that of the measuring vehicle and, if negative, said speed is added to the speed of the measuring vehicle to make it possible to accurately measure the true speed of the vehicle to be measured. By this method, the generation of an error can be prevented in the measurement of speeding.