PURPOSE: To drive a car in a non-visual field, by arranging a plurality of Doppler transmitter-receivers and making it possible to confirm the distance up to a target.

CONSTITUTION: Six Doppler transmitter-receivers 2W7 are provided to a driven car 1 and measure the distance between the driven can 1 and a target on the basis of the time required between the point of time when a radio wave is transmitted to a target from each of the transmitter-receivers and the point of time when the reflected radio wave from the target reaches each of the transmitter receivers. For example, the radio waves emitted from the transmission parts of the transmitter-receivers 2, 3 are reflected from the symmetric reflecting point A of a car 8 and received by the receiving parts of the transmitter-receivers 2, 3. At this time, the angles of rotation of the transmitter-receivers 2, 3 are inputted to a microcomputer to perform the processing of information to automatically measure and display the distance between the driven car 1 and the car 8. Therefore, the distances between the driven car 1 and the front car 8, the rear car 9 and a medial divider 10 are set within a predetermined range and an alarm is emitted when the driven car 1 is deviated from said range and the distance between the driven car 1 and the target is kept constant to make it possible to smoothly perform the driving in no field.