Booking venders are to be enabled to issue booking certificates without having to consume their own resources. Advance booking is made and sent to a retailer from a consumer terminal via the Internet. The retailer requests a booking certificate issuing center to issue a booking certificate associated with the product or the booking party, and receives the booking certificate issued from the booking certificate issuing center. The consumer terminal receives the booking certificate from the retailer via the Internet, and uses it to have itself verified to be the legitimate booking party by a verifying apparatus associated with a provider. The booking party can receive the supply of the booked product or service if its booking certificate is successfully verified.