An information recording medium (1) includes a recording area (12) in which a content (122) which is encrypted by an encryption key in a first encryption system and first key information (121) for obtaining the encryption key by a second encryption system that is different from the first encryption system are recorded and a control information area (11) in which second key information (112) for obtaining the encryption key by at least first encryption system and a flag (111) for deciding which system is to be used, either the first encryption system or the second encryption system, are recorded. At the time of reproduction, when the encryption key is obtained by the system decided by the flag and the content is reproduced, the content can be properly protected while keeping compatibility with the existing content protection technology.