A method for erasing a first sub-block of a plurality of sub-blocks included in a block of a non-volatile memory device, wherein the first sub-block includes at least one word line, includes applying an erase voltage to a substrate, applying a third voltage lower than the erase voltage to the word line of the first sub-block, applying a first voltage at least one word line adjacent to the word line of the first sub-block, and applying a second voltage that is the same as or similar to the erase voltage to the other word lines, where the first voltage has a level between the third voltage and the second voltage.