A leadership support system includes a leader terminal and plural member terminals. The member terminals, according to either the relay of communication information not addressed thereto or the reception of communication information addressed thereto, send back a response to the appropriate communication information. The leader terminal determines, based on the times of relaying the communication information, whether or not the member terminal that transmitted the communication information is in danger of isolation. When the leader terminal determines the member terminal in danger of isolation, it outputs a warning signal indicative of a ranger of isolation to that member terminal.