A system includes at least one controlled device that is controlled based on control information output from an external device, and an image forming apparatus that forms an image on a recording material and communicate with the external device and the controlled device, wherein the image forming apparatus includes a transceiver that receives the control information from the external device and transmits the control information to the controlled device, and a transmission controller that stops the transmission of the control information by the transceiver or changes contents of the control information to be transmitted by the transceiver.