A reservation system for an article or a service includes an input module obtaining a weather forecast, a module setting a price of the article or a charge for the service in accordance with the weather forecast obtained, an accept module accepting a reservation for purchasing the article at the set price or a reservation for utilizing the service at the set charge, and a module issuing a reservation number for uniquely identifying the reservation accepted, and identifying a reserver making the reservation from the reservation number when purchasing the article or when utilizing the service.