To provide a technology for preventing deterioration in the efficiency of the whole relay communication system by reducing a load of a relay server.

A shared resource 86 is shared by client terminals 11, 21, 22 and 31, and managed by shared resource management information 82 held by each client terminal. The client terminal 11 classifies each shared resource into groups corresponding to an owner client terminal when acquiring the copy of a plurality of shared resources 86. The client terminal 11 uses a communication path established between the client terminal and each owner client terminal, and acquires the copy of the shared resources 86 by each group unit in a batch. When continuously acquiring the copy of the shared resource 86 from the client terminals 21 and 22, the client terminal 11 establishes a communication path to the client terminal 22 by reusing the communication path to the relay server 23 among the communication paths established between the client terminal and the client terminal 21.