A traffic system including a first vehicle and a second vehicle. The first vehicle includes a communication unit, a detection device detecting an external situation around the first vehicle, and a microprocessor configured to perform recognizing a moving object based on the external situation detected, determining whether there is an approach risk indicating that a distance from the second vehicle to the moving object becomes equal to or shorter than a predetermined value, and outputting an approach signal when it is determined that there is the approach risk. The second vehicle includes a communication unit, a warning unit issuing an alarm outside of the second vehicle, and a microprocessor configured to perform controlling the warning unit so as to issue the alarm when the approach signal output from the first vehicle is received through the communication unit.