PURPOSE: To share functions inside a system by plural devices by judging whether or not the function indicated by the acquired function information of plural output devices and the function requested from an outside coincide and selecting the output device provided with the coincident function as the result.

CONSTITUTION: An external device 22 is electrically connected with a reader part 211 and provided with the various kinds of the functions, an interface part 221 is for connecting the other devices connected on a network and an image memory part 224 is constituted of a RAM or the like for tentatively storing information transmitted from the other device on the network and the information from the reader part 211. A facsimile part 222 transmits and receives image data stored in the image memory part 224, a formatter part 223 converts printing commands transmitted from the other device to the image data and stores them in the image memory part 224 and a core part 225 controls the external device 22 and a main body device 21.