In a conventional voice dialogue system, there is a case where it is difficult to perform a natural dialogue with the user. Therefore, we designed to perform speech recognition on the user's utterance, to control a dialogue with the user according to a scenario previously given, based on the speech recognition result to generate an answering sentence corresponding to the contents of the user's utterance as the occasion demands, and to perform voice synthesis processing to one sentence in the reproduced scenario or the generated answering sentence.