[PROBLEMS] To suppress the occurrence of fragments of an index file that manages content files recorded in a recording medium. [MEANS FOR SOLVING PROBLEMS] Content files and an index file, which manages the content files, are recorded on an optical disc (2). The index file comprises attribute information of the content files (text data of titles, thumbnail image data and so on). A microcomputer (19), when recording a particular content file onto the optical disc (2), updates the index file such that the particular content file is registered with the index file. In this case, the microcomputer (19) reserves, in the index file, a predetermined number of successive slots having a fixed length, and allocates the attribute information of the particular content file to those slots. The predetermined number may be set to, for example, the maximum or average number of slots that can be predicted for use in registering the content file.