PURPOSE: To prevent the generation of unauthorized copy by comparing two coded data read out by respective coded data readers in two medium driving devices, and only when both data coincide with each other, allowing copying between two media.

CONSTITUTION: A copying source medium 4a in which original information is written and a copied medium 4b in which information is to be copied are prepared. A CPU 1 compares coding data read out of respective media 4a, 4b and when both data disaccord with each other, disables a disk driving device 3 to inhibit copying. Namely, a medium having no same coded data as that of the copying medium can not copy the information of the original medium. Thereby, unauthorized copying by a medium other than an authorized specific medium can be suppressed by adopting a system such that a medium in which coded data are written or the seal of coded data only to an object authorized to copy the information.