A vehicle detecting system for detecting the number of vehicles which pass the roadway, thereby realizing the smooth flow of vehicles. This system comprises: a transmitting coil and a receiving coil which are arranged on both sides of the vehicle detection area set over the roadway; a driving circuit to supply a high frequency exciting current to the transmitting coil; and vehicle detecting circuit to output a vehicle detection signal in response to a change in level or phase of the electrical signal which is induced in the receiving coil. The detection signal is outputted when the signal level exceeds a predetermined value or when the signal phase exceeds a predetermined angle. One or a plurality of pairs of transmitting and receiving coils may be buried under the roadway surface or on above the roadway at regular intervals. With this system, the installing construction of the coils is simplified and the possibility of the occurrence of the accident such as disconnection of the coil is reduced. The vehicle on the roadway can be certainly detected.
