A method and apparatus for preventing generation of third generation data of an original data recorded on a read-only region of a partial read-only memory (ROM) optical disk includes an operation for copying source data from the partial read-only memory to a read-write medium by first attempting to write check data on a read-write region of the partial ROM optical disk. If the check data cannot be written, the copy operation terminates. If the check data can be written, the source data is overwritten. Then, the source data is copied from the partial ROM optical disk to the read-write medium.