If playback devices are prohibited from playing back contents recorded in R media, there occurs a problem that it takes more time to manufacture commercial ROM media. Conversely, if playback devices are permitted to play back contents recorded in R media, there occurs a problem that copyrights might be infringed. In view of these, the aim of the present invention is to provide a content protection data processing system and a playback device capable of determine whether to permit playback of a content recorded in a recording medium, based on a medium type of the recording medium and a signature type of a signature attached to a program. This enables both the protection of the copyright of the content and the efficient manufacturing of commercial ROM media.