In a checkout system, a registration apparatus is set to be capable of executing data communication with any one of a plurality of checkout apparatuses before data input of a commodity purchased by a customer at the registration apparatus is started or during a period from the start to the termination thereof. Details of the commodity of which the data is input in the registration apparatus capable of executing data communication with any one of the checkout apparatuses capable of executing the data communication are displayed on a display of the corresponding checkout apparatus before the data input of all commodities purchased by the customer is terminated. Settlement is executed based on input payment data at any one of the checkout apparatuses capable of executing the data communication if the data input of all the commodities purchased by the customer in the registration apparatus is terminated.