A traffic information detection system and method. According to the traffic information detection method of the present invention, at least one loop coil on a road transmits a signal indicative of electric change induced in the loop coil by a vehicle, at least one loop detection device installed at the garden or escape zone of the road receives the signal transmitted from the loop coil and wirelessly transmits a signal indicative of whether or not a vehicle exists on a road, the velocity of and type of the vehicle, and a traffic signal controller wirelessly receives the signal transmitted from the loop detection device, thereby acquiring traffic information.