When preparing print data by a personal computer, identification data corresponding to the print data is also prepared. The print data is transmitted via a network to a printer, and the identification data is transmitted to a portable phone by wireless, and stored in a memory in the portable phone. When a user approaches the printer carrying the portable phone, the identification data is transmitted to the printer by wireless. The printer carries out image output processing based on the print data corresponding to the received identification data. Thus, in a control system for an electronic device such as an image output device, operation control can be conducted by each print job, and by such operation control, the whole system including an electronic device and data preparation means such as a personal computer can be controlled more efficiently.