To provide an inventory centrally-managing system which enables a manufacturing plant side to manage the inventory control of products, reduces a load on an each-site sales company conducting a management task for shipment to a manufacturing plant, and prevents a delay in shipment to a customer.

Inventory information, order-placement information and order-reception information, all of which each-site sales company has, are extracted. The extracted data are stored in a site basic device accompanying a site server. The business/inventory information stored in each-site basic device is stored in a central basic device at a spot and can be browsed by each manufacturing plant and each overseas manufacturing company.