Memory device for performing post package repair (PPR) operation

A memory device for performing a post-package repair (PPR) operation is disclosed. The memory device receives the post-package repair (PPR) command and the defective row address from the memory controller, stores the defective row address in the nonvolatile memory or volatile memory according to the PPR command, and the defective word line selected by the defective row address And performs a PPR operation for writing data into redundant memory cells connected to the redundant word line to be replaced. In the redundancy memory cells, data of memory cells connected to the defective word line are written or data `0` or data` 1` is written.