A medium writing apparatus obtains information to be written onto a recording medium, converts the information into a suitable writable format, and then writes the converted information onto the recording medium. An ID obtaining section obtains a medium ID from the recording medium, or through an input by the user. The medium ID and information indicating the place of the written information are sent to a server, and then stored as index information correlating them with each other. When the information written onto the recording medium is to be used at a later timing, the medium ID is identified, and the index information is obtained from the server. Therefore, the original information can be obtained so as to be easily reprocessed or reused.