Provided are methods of operating NAND nonvolatile memory devices. The operating methods include applying a read voltage or a verify voltage to a selected memory cell from among a plurality of memory cells of a cell string to verify or read a programmed state of the selected memory cell; applying a first pass voltage to non-selected memory cells closest to the selected memory cell of the cell string; applying a second pass voltage to second closest non-selected memory cells to the selected memory cell; and applying a third pass voltage to other non-selected memory cells, where the first pass voltage is less than each of the second and third pass voltages and the second pass voltage is greater than the third pass voltage.