An on-the-fly repair method for a memory includes: performing a block erase operation on the memory; checking whether the block erase operation is passed or not; finding whether there is any available and healthy redundancy block in the memory if the block erase operation is not passed; programming an address of a failed block to be repaired, an enable bit and at least one error correction bit into both first and second redundancy information regions in a redundancy information set of the memory; checking whether error in the first and the second redundancy information regions is recoverable based on the error correction bit; and if the error is recoverable, then programming the redundancy information set as effective to replace the failed block by the redundancy block related to the effective redundancy information set.