To provide a technology for establishing a communication session of a cascade configuration comprised of a plurality of communication terminals to attain a remote conference without installing a controller which controls the communication terminals and without troubling users of the respective communication terminals.

A master terminal establishes the communication session with a partner terminal specified in a terminal list by referring to the terminal list in which, with which of other communication terminals the communication session should be established. The partner terminal which completes the establishment of the communication session establishes the communication session with the communication terminal specified by the terminal list by referring to the terminal list received from the master terminal. Thus, the communication session in the cascade configuration is established between the plurality of communication terminals by sequentially performing the establishment processing of the communication session and the transfer of the terminal list with the partner terminal specified by the terminal list by the respective communication terminals.