The present invention relates to a method of correcting data on a high-density recording medium such as a BD-ROM (Blu-ray ROM Disk) and a BD-RW (Blu-ray ReWritable Disk). In the present method, whether there is any error in a predetermined-sized LDC data block, which is included in a physical cluster, is determined based on if there is an error in sync data and BIS data neighboring the LDC data block, and, if determined to be erroneous, error correcting operation for the LDC block is conducted.