To protect copyrights or the like of music, sound, visual images, etc., broadcast by televisions, radios, etc., or recorded in CDs, cassette tapes, video tapes, etc., in acoustic appliances, video appliances, etc., capable of recording/reproducing, etc., the music, sound, visual images, etc.

When a television broadcast program, a radio broadcast program or the like is to be recorded, etc., by an acoustic appliance, a video appliance or the like, or when sound, voice, images or the like are to be recorded, etc., from a CD, a cassette tape, a video tape or the like, a production number, random numbers or the like proper to the recording acoustic appliance, video appliance or the like are simultaneously recorded to recording parts 1-4 of a recording medium 5 such as a cassette tape, a video tape or the like. When the music, voice, images or the like are to be reproduced, etc., from the recording medium such as the cassette tape, video tape or the like, the music, voice, images or the like cannot be reproduced if a using acoustic appliance, etc., does not have the same number as the production number, random numbers or the like of the acoustic appliance, video appliance or the like which is recorded to the medium.