A scheme for constructing a database in a user system, which can automatically store those portions of the structured documents which contain important contents without exerting a burden on the user is disclosed. A structured document provided by a server device is obtained according to a document request made by the user system, where each structured document has a structure represented by tags in each structured document. Then, at least one important portion is automatically extracted from the structured document by utilizing the structure of the structured document according to prescribed extraction criteria specified in advance, and the extracted important portion is stored into the database, while the obtained structured document is transferred to the user system.