Disclosed is technology capable of improving operability of a multi-function image processing apparatus with simple inexpensive structure and easily designing necessary system software. After start-up, the apparatus is connected to an IPv6 router on a network, prefix information is acquired from the router, there is generated an IP address unique to each of image processing functions such as printing, scanning and FAXing on basis of the acquired prefix information, the apparatus communicates with other appliance on the network by use of the IP address generated for every image processing function, and each image processing function operates corresponding to a result of the communication. Transfer task transfers data to be inputted and outputted among print task, scan task and facsimile task by use of IP addresses each different for every function, and the respective tasks run on a time-division basis using a task switchover by OS.