A response unit located on a vehicle performs transmission operations for transmitting signals including a pilot response signal responsive to receipt of a pilot signal from a fixed transceiver. The transceiver uses a highly directive transmission antenna to transmit a beam-shaped signal containing a pilot signal to a communication zone set with respect to a lane along which the vehicle travels. The fixed transceiver also performs data transmission/reception operations with the response unit when it receives a pilot response signal therefrom. The beam-shaped signal is set to have a radiation area smaller than the area of the communication zone and is electronically scanned within the communication zone in a direction orthogonal to the movement direction of the vehicle by a scanner in the transceiver. The scan patterns of beams from transceivers corresponding to adjacent lanes are synchronized so that the scan areas of signals from adjacent transmission antennas do not overlap.