A content providing system includes: a server which provides to a host apparatus a first encrypted content including an encrypted area having applied thereto a replacement key; a host apparatus which receives the first encrypted content and replacement key application area information indicating the encrypted area having applied thereto the replacement key from the server; and a data storage device which receives the replacement key from the server and an individual key set in terms of content distribution processing from the server and performs key replacement processing for changing the replacement key application area of the first encrypted content to an encrypted area by the individual key to store a second encrypted content after the key replacement processing in a data recording area.