Memory system and wear leveling method thereof

Disclosed is a memory device including a NVRAM and a page table, and a wear leveling method therefor. The page table includes mapping information which maps virtual addresses of the NVRAM with physical addresses of the NVRAM. A page table entry includes aging information which indicates the wear of a corresponding page. The aging information may be a remaining number of write operations allowed to the page. Whenever data is written in a page, a value indicating a remaining number of write operations allowed to that page is decremented.