A method of driving a nonvolatile memory device including applying a reset voltage to a unit memory cell, reading a reset current of the unit memory cell, confirming whether the reset current is within a first current range, if the reset current is not within the first current range, changing the reset voltage and applying a changed reset voltage or applying again the reset voltage to the unit memory cell after applying a set voltage to the unit memory cell, if the reset current is within the first current range, confirming whether a difference between the present reset current and an immediately previous set current is within a second current range, and, if the difference is not within the second current range, applying the reset voltage or applying again the reset voltage to the unit memory cell after applying a set voltage to the unit memory cell.