To allow sellers of consumable products to manage a number of customers' products using public lines.

If a customer signs a contract with a seller, the seller delivers a storage container 3 to the customer and then the storage container 3 is connected to a management computer system 1 of the seller via public lines 2. The storage container 3 is provided with a data processor 11, a product identification sensor 8, and a remaining sensor 9. The data processor 11 regularly reports the remaining amount of a consumable product to the management computer 1. The management computer 1 predicts a use completion day of the consumable product, and calculates days necessary to deliver. Then the management computer 1 allows the data processor 11 in the storage container 3 to ask the customer whether or not to order. If the customer orders, the management computer 1 restocks the consumable product.