A content data storage apparatus that enables content data on a plurality of client apparatuses to be individually updated according to the preferences or the like of users. Content data on a memory card is stored in association with client content management information for managing the content data and client content identification information for identifying the content data in management units. When client content identification information stored on a memory card connected to an input/output unit matches any storage content identification information stored on a hard disk, a control unit updates the content data of the memory card based on content data included in management units identified by this storage content identification information.