PROBLEM TO BE SOLVED: To provide a system for selecting attribute information concerned with a document and registering the attribute information in an item management server even when a user cannot directly access the item management server.SOLUTION: An image processing apparatus receives a document from an external apparatus, acquires attribute information indicating information concerned with an item from an item management server and transmits the received document and the attribute information in each acquired item to a document management server. The document management server presents information of the transmitted document and attribute information of the transmitted item to the external apparatus in accordance with a request from the external apparatus, receives association information associating the document with the item, selected by the presented information, from the external apparatus, and registers the document concerned in the item management server together with the association information.