Portable information devices each include a portable-side communication unit to communicate with an image processing apparatus within a range of a predetermined distance, and a portable-side control unit. The portable-side control unit executes the steps of: specifying a linked process; displaying an operation screen for accepting a setting value corresponding to the linked process in a state in which the portable-side communication unit is unable to communicate with the image processing apparatus; accepting a setting value from a user; in response to the portable-side communication unit becoming able to communicate with the image processing apparatus, transmitting a setting request and receiving a response to the setting request from the image processing apparatus; if the response indicates to start the linked process, transmitting/receiving data in cooperation with the image processing apparatus; and if the response requests a setting value, displaying an operation screen for setting the requested setting value.