A file system which is enabled to use a Metadata Partition instead of VAT for write-once discs, is provided by a pseudo-overwrite method. On applying this invention to a drive apparatus which supports pseudo-overwrite media, the file system distinguishes data to overwrite from data to append. When the data is newly written to a logical sector, the drive apparatus writes the data to a physical sector to which the logical sector corresponds. When the logical sector is overwritten the data is written to another unrecorded physical sector in the volume space, and remapping information that specifies the original address, and the remapping address are stored in the remapping table.