In a document-management device in an embodiment of the invention, a printing unit prints an automatic registration request page on a sheet in response to a print request from a user on a screen displayed on a client. A data receiving unit receives scanned image data containing image data of paper documents and image data of the printed sheet. An information acquiring unit receives a portion of the automatic registration request page separated from the scanned image data, to acquire information of a site identifying code. A registering unit registers a remaining portion of the scanned image data to an existing system according to the information of the site identifying code.