The objective of the present invention is to manage reference movies using an index file, without causing the user to be perplexed. the reference movies are generated because of, for instance, the upper limit of the file size. The index file manages sets of information regarding the files being managed. Examples of these sets of information are information for determining whether or not a file is presented to the user, information for determining whether or not a file is original, and information indicating whether or not nondestructive editing has been done. Based on such information, the erasure, displaying a list, and so on are carried out. Thus, it is possible to manage the reference movies using the index file, without causing the user to be perplexed.