To form a guidance sentence against which a user does not feel discomfort when the user performs invalid utterance to a question, confirmation by guidance from an interaction system and when guidance of the same content becomes necessary again because the system performs erroneous recognition.

This speech interaction system is constituted so that it comprises a judgment means which judges whether a reply targeted by the guidance sentence is obtained or not from a reply sentence and a retry request means which outputs an other difference guidance sentence for obtaining the targeted reply and requests a reply sentence to a speaker again when it is judged that the targeted reply is not obtained by the judgment means.