A mobile computer supporting system realizes communication even when a communication protocol address is to be dynamically changed due to movement of the computer, or the like. When a PC has moved, it notifies an AMS of a changed present address together with its home address. The AMS stores the home address and present address of each terminal, so as to correspond to each other, into an address correspondence table. When a PC sends and receives information to and from the PC, a socket hook processing of the PC acquires the information when the home address of the PC is added to the information. The socket hook processing inquires of the AMS of the present address of the PC using the home address of the PC, converts the home address of the PC added with the information to the present address obtained by the inquiry, and sends the information after conversion to a socket processing.