An operating method of a memory system includes storing normal data to a first storage area of a non-volatile memory in a first program mode among multiple program modes defined according to a number of bits stored in each memory cell; storing dummy data in the first storage area in at least one of the multiple program modes including the first program mode; and copying the normal data from the first storage area to a second storage area of the non-volatile memory based on dummy data stored in the first program mode.