In a case in which an operation is alternately carried out by apparatus-1 and the apparatus-2 in cooperation with a robot, an operator carries out operation within an operation range of each of the apparatuses during the interruption of power supply to the apparatus-1 and the apparatus-2. Even if the operator approaches or enters the apparatus-1 or the apparatus-2, an emergency stop unit is not informed of a notice of such approach or entry as far as the interruption of power to the apparatus is confirmed. In a state in which the interruption of power is not confirmed, on the other hand, the emergency stop unit is informed of the notice of operator's approach or entry, and the robot system is emergency stopped.