The present invention discloses a method for performing a defective-area management adaptive to a slipping replacement algorithm in an optical media with segmented sector/blocks, by either keeping buffering a read user data of the sector/block to a buffer memory, regardless of the read sector/block is defective, or keeping buffering the read user data to two different memories based on whether the sector/block is defective, thereby simplifying the complicated steps due to absence of interruption of data buffering, and therefore raising an operating performance.