PURPOSE: To measure the distance to a stationary body from a measuring point on a moving body through a simple device, by operating and processing the outputs of an image pickup unit, a timer and a speedometer.

CONSTITUTION: A stationary body is caught in the form of an image by an image pickup unit 21. An elevation angle θ1 at certain time t1 and another elevation angle θ2 at the present time t2 are calculated by a computation circuit 24 from video signals from the image pickup unit 21. The period (t) from the time (t1) to the other (t2) is measured by a timer 22. A speedometer 23 detects its own moving speed (v). An operation circuit 25 calculates the distance θ1.v.t/(θ2-θ1) between the stationary body and a moving body on the basis of the outputs of the computation circuit, the timer and the speedometer.