Where a recording medium recorded on at a slave side apparatus is reproduced, it has been made possible to perform on cite modification processing identical to that conducted at a master side apparatus, by reproducing, at the master side apparatus, the primary information added with parity symbol for error correction from the recording medium on which the primary information is recorded, correcting the symbol error of primary information reproduced at the reproducing means using the reproduced parity symbol, producing the flag which indicates the production of an uncorrectable symbol error in one unit of a block of a specified amount of information and thus outputting the modification information corresponding to the primary information and the flag and forming, at the slave side, the parity symbol for correction of error of primary information output at the master side apparatus and recording the primary information with the parity symbol and modification information, on the same recording medium. It has also become possible to conduct satisfactory modification processing when the symbol error is produced.