A connection control method of controlling connections among a plurality of terminals through a network, the method comprising the steps: managing identification information for identifying a terminal, and identification information for identifying one or more candidate terminals that are associated with the terminal, for each one of the plurality of terminals; managing session information for a session comprising identification information for identifying one or more terminals (10aa, 10db) that are participating in the session; receiving a request for participating in the session from a participation requesting terminal that is not participating in the session; extracting (S106-1) identification information for identifying at least one candidate terminal that is associated with the participating terminal (10aa, 10db) for each one of the plurality of participating terminals (10aa, 10db) to obtain extracted candidate terminal identification information of the participating terminals; determining (S106-3) whether the extracted candidate terminal identification information of the participating terminals includes identification information for identifying the participation requesting terminal to generate a first determination result; determining (S 106-7, S 106-8) whether to allow the participation requesting terminal to connect with the plurality of participating terminals (10aa, 10db) through the network to participate in the session, based on the first determination result characterized by the following step being performed upon connecting the participation requesting terminal and the participating terminals (10aa, 10db): associating identification information for identifying the participation requesting terminal, allowed to participate in the session, with the session information. managing identification information for identifying a terminal, and identification information for identifying one or more candidate terminals that are associated with the terminal, for each one of the plurality of terminals; managing session information for a session comprising identification information for identifying one or more terminals (10aa, 10db) that are participating in the session; receiving a request for participating in the session from a participation requesting terminal that is not participating in the session; extracting (S106-1) identification information for identifying at least one candidate terminal that is associated with the participating terminal (10aa, 10db) for each one of the plurality of participating terminals (10aa, 10db) to obtain extracted candidate terminal identification information of the participating terminals; determining (S106-3) whether the extracted candidate terminal identification information of the participating terminals includes identification information for identifying the participation requesting terminal to generate a first determination result; determining (S 106-7, S 106-8) whether to allow the participation requesting terminal to connect with the plurality of participating terminals (10aa, 10db) through the network to participate in the session, based on the first determination result characterized by the following step being performed upon connecting the participation requesting terminal and the participating terminals (10aa, 10db): associating identification information for identifying the participation requesting terminal, allowed to participate in the session, with the session information. associating identification information for identifying the participation requesting terminal, allowed to participate in the session, with the session information.