The clients visiting through the internet subscribe to a billing center and select either an advance or a deferred payment. In case of an advance payment, an exchange ticket is purchased and is used for payment. The contents provider willing to adopt the billing system according to the present invention should join through the billing center, set up a billing client program and construct directories and service files according to a billing plan. The constructed directories and service files are registered as menus in the billing center. The service provided to a client in a contents provider's site through the internet is charged according to a menu registered in the billing center. The payment of a bill is performed through a financial agency which is connected to the billing center via a payment gateway. |