To provide a document management system and a document management method that can duplicate a document in a document management server into another document management server upon a client's instruction.

A client terminal 1 transmits a duplication request to a document management server 2, and the document management server 2 transmits a certificate showing the authority to operate the document management server 2 to the client terminal 1 in response to the duplication request. The client terminal 1 receives the certificate and transmits it to a document management server 3, and the document management server 3 receives the certificate and transmits it to the document management server 2. The document management server 2 transmits the document for which the duplicate request is made and which is stored therein to the document management server 3, and the document management server 3 duplicates therein the document transmitted from the document management server 2.