Abstract: A natural language conversation system is capable of making interaction between the user and the system smooth by continuing conversation with presenting guidance or with making the system to carry out speech for the user when user cannot response to presentation of the system to cause non-response, and can reduce load required for speech of user. The natural language conversation system includes conversation control portion for outputting data in a conversation scenario, and alternative conversation portion for alternatively inputting a preliminarily prepared natural language data to the conversation control means on behalf of a user when the user fails to input within a predetermined period.