To provide a signal transmitting method for preventing robots from colliding with each other in a control system for a self-traveling robot.

A signal transmission path 5 using an L-C resonance circuit is provided along the route of a self-traveling robot. A reactance part of the signal transmission path 5 is a loop antenna having at least one electrically unconnected cross lines, and the loop antenna cancels external noises. The self-traveling robot is provided with a transmission antenna 8 and a reception antenna 9. The transmission antenna 8 transmits a signal showing the existence of the self-traveling robot itself, the reception antenna 9 receives a signal transmitted by another robot to thereby detect an approaching robots to each other, preventing the self-traveling robots from colliding with each other.