A traffic management system manages, distributes, and controls various traveling states of vehicles at a high quality level. A vehicle-mounted unit performs an interconnection process for user authentication when entering a predetermined radio-wave zone. A radio unit disposed on a road sends interconnection process completion information to a center device when the interconnection process for connection to the vehicle is completed. If the vehicle does not connect to the radio unit after elapsed of a predicted time at which the vehicle is expected to travel across the radio unit, then the radio unit sends an overtime to the center device. The interconnection process completion information is received, the center device calculates a predicted time at which the vehicle is expected to pass across a radio unit, and sends the predicted time to the radio unit. When the overtime is received, the center device determines whether a fault has occurred or not. When it is judged that the fault has occurred, the center device sends alarm information to vehicles traveling near a site where the fault has occurred on the vehicle.