With an object of disclosing various techniques for both usage and protection of content, the present invention has an object of providing a playback control apparatus, a position judgment apparatus, and a playback control system that permit playback of content only in one area. In other to achieve the object, with the present invention, when a user passes through an automated ticket barrier to enter a station, the automated ticket barrier transmits, to a memory card via the mobile telephone, a playback key for playing content. When the user passes through an automated ticket barrier to leave a station, the automated ticket barrier instructs the memory card, via the mobile telephone, to delete the playback key, and the memory card deletes the playback key.