This paper proposes a system to control mobile robots by applying traffic rules. The authors have constructed traffic rules to achieve safe and smooth movement of robots by collectively considering information on the work environments of mobile objects such as mobile robots and persons. The traffic rules enable respective mobile robots using self-control to judge their movement. The system applies the traffic rules to mobile robots in order to coordinate a certain range of movement through maximum use of information on the environments of mobile robots such as their passages∗ quantity, performances, and which are usually are known. Applying traffic rules to robot movement in order to coordinate robots is a new proposal, enabling the realization of a system that needs no direct communication such as a communications system. This paper first outlines a traffic rules application system for mobile robots, and explains how to construct the system by showing examples. Also, the paper discusses the effects of the system, and how to apply the traffic rules to actual systems. Finally, the paper explains the effectiveness of the system that applies the traffic rules, and the attainment of mobile robots using the system through experiments with mobile robots mounting ultrasonic sensors.