PURPOSE: To detect a speed of a vehicle and an angular velocity from two space filter units by installing the space filter units on a shaft parallel to a rear axle in a plane vertical to a road surface, by setting its vertical stripe direction to a direction of the rear axle.

CONSTITUTION: The installing position of space filter units 1, 2 are provided on two places on a straight line which is one the rear axle P3, P4 or parallel to the rear axle P3, P4 in a plane vertical to a road surface. Electric signals f1, f2 of a frequency detected by the units 1, 2 are connected to photoelectric converters (F-V) 5, 6 through amplifiers 3, 4. Its output signals V01, V02 are made to branch, and one of them is connected to speed meters 7, 8 and the other is connected to an angular velocity meter 10 through a differential amplifier 9. A signal V03 is a voltage signal proportional to a difference between a speed V1 and V2 and a signal proportional to an angular velocity ω. The electric signal V01, V02 and V03 connected to the speed meters 7, 8 and the angular velocity meter 10 are connected to a navigation system 11, and an advance direction and a present position of a vehicle can be displayed by these speed information and angular velocity information.