A method for operating a memory system includes: collecting, by a memory controller, information on rows that are determined as row-hammer-attacked in a memory by the memory controller; collecting, by the memory, information on rows that are determined as row-hammer-attacked by the memory; confirming, by the memory, that the row collected by the memory controller is the same as the row collected by the memory; and resetting, by the memory, information on the row collected by the memory which is the same as the row collected by the memory controller in response to the confirmation.