To improve the measurement precision of the traveling speed of a vehicle.

Light emission units 36a and 36b emit two light beams B1 and B2 to positions on a travel road of the vehicle which are at specific intervals ΔL in the traveling direction and light reception units 42a and 42b receive reflected lights of the light beams B1 and B2 from the travel road or vehicle. Pulse counting circuits 34a and 34b measure the reflection time T1 of the light beam B1 and the reflection time T2 of the light beam B2 and a 2nd pulse counting means 52 counts the travel time ΔT from the time T1 when the reflection from the vehicle is sensed to the time T2 when the reflection from the vehicle is sensed. Then a controller 60 computes the traveling speed V from the travel time ΔT needed for the vehicle to travel the interval ΔL.