Even if contents data distributed over a network are once destroyed, the contents data are restored, as the copyright protection is maintained. A PC memorizes backup of distributed music contents on a hard disc, at the same time as it transmits the using log information of the music contents stored in the hard disc to an EMD server. If the music contents in the hard disc are destroyed, the PC acquires the using log information from the EMD server to reproduce the backup data memorized in the hard disc depending on the using log information.