Mobile communication apparatus, of small size and low cost, may be installed in vehicles to afford enhanced mobile-to-mobile communications between preceding and succeeding vehicles, even over a great distance therebetween. In the preceding vehicle, a detector detects a carrier transmitted from the succeeding vehicle and a transmission controller uses the carrier, when detected, for transmitting data to the succeeding vehicle. Further, the detector in the preceding vehicle detects, from the carrier transmitted from the succeeding vehicle, whether the distance to the succeeding vehicle is in a range permitting two-way communications therebetween. The transmission controller in the preceding vehicle transmits first information to the succeeding vehicle when the detector does not detect the possibility of two-way communication, and transmits second information to the succeeding vehicle when the detector detects the possibility of two-way communications with the succeeding vehicle.