A receiving unit (310) receives a message transmitted from any one of the users that are talk targets. The interpreter (341) attempts to interpret, as an answer to a question, the message received by the receiving unit (310). A collector (342) collects, upon success of the attempt made by the interpreter (341), the interpreted answer as the answer from the user who sends the message. When a predetermined requirement is satisfied in a state where a yet-to-respond user whose answer is not yet collected by the collector (342) is present, an inquiry transmitter (321) transmits an inquiry about the question to at least the yet-to-respond user among the users. A result transmitter (322), after the answers are collected from all of the users, transmits to the users a message indicating a result obtained by tallying the answers.