Memory controller and memory system having the same

A memory system includes a memory controller. The memory controller includes: a buffer memory configured to store read count values of memory blocks and address mapping information of the memory blocks; and a central processing unit configured to monitor the read count values, and determine whether a refresh operation of target blocks, among the memory blocks, is to be performed on all memory blocks including target blocks in a super block, in a unit of the super block or on the target memory blocks in the super block in a unit of a single block, based on the monitoring result.