The present invention improves a sense of participation in a topic and enables a dialogue to continue for a long time. A dialogue system 12 includes at least an input part 1 that receives a user's utterance and a presentation part 5 that presents an utterance. In an utterance receiving step, the input part 1 receives an utterance performed by the user. In a first presentation step, the presentation part 5 presents an utterance determined based on scenarios stored in advance. In a second presentation step, the presentation part 5 presents the utterance determined based on the user's utterance contents. A dialogue control part 8 performs control to execute a dialogue at least including a first dialogue flow which is a dialogue including the utterance receiving step and the first presentation step at least one time respectively based on a predetermined scenario, and a second dialogue flow which is a dialogue including the utterance receiving step and the second presentation step at least one time respectively.