According to an example embodiment of the inventive concepts, an operating method of a memory system including a memory controller and a non-volatile memory device, the non-volatile memory device being operated under control by the memory controller and the non-volatile memory including a first memory block and a second memory block, the method includes determining, by the memory controller, whether the first memory block satisfies a block reset condition, in response to the first memory block satisfying the block reset condition, applying a turn-on voltage to word lines of dummy cells included in the first memory block, transferring data pre-programmed in the first memory block to the second memory block, erasing the first memory block, and re-programming the dummy cells of the first memory block.