A file-update apparatus, which can mount a removable information recording medium storing a FAT and a directory entry that show a storage location, on the medium, of data constituting a content of a file, and which executes a plurality of update procedures to update the file, records progress information showing which of the update procedures have been executed in updating the file into an internal memory having a continuous power supply. Even if an abnormal stoppage of the update procedures caused by a power-down or the like occurs during updating of the FAT, for example, the progress and update information remain in the memory. Thus, the FAT and the like can be re-updated and inconsistencies resolved using this information, after recovering from the abnormal stoppage.