Information processing device, information processing method, information processing program, recording medium storing the program and player

There is provided a player which efficiently restricts reproduction of information. The type of a recording disk (1) is determined by a disk distinction unit of a microcomputer (130), and a reproduction processing is immediately started unless the recording disk is determined as a DVD. If the disk is determined as a DVD, a key-bunch determination unit of the microcomputer (130) determines whether MKB information as a content for protection according to the CPPM technique is recorded or not. If not recorded, the reproduction processing is started immediately. Otherwise, if recorded, a wobble signal determination unit of the microcomputer (130) determines whether a wobble exists or not. If a wobble does not exist, the reproduction processing is started immediately. If a wobble exists, a restriction unit of the microcomputer (130) determines whether information has been properly recorded or not. If the information is an illegal copy, reproduction is inhibited. Reproduction of illegal copies is thus securely and efficiently restricted.