A memory system is provided. The memory system includes a memory device having a plurality of memory cells; and a memory controller configured to control the memory device to: store write data in first memory cells from among the plurality of memory cells, identify a current charge amount of a first cell string including at least one of the first memory cells and a current charge amount of a second cell string adjacent to the first cell string, and store dummy data in at least one memory cell connected to the first cell string or the second cell string based on the current charge amount of the first cell string and the current charge amount of the second cell string.