A first verify voltage is applied to a word line of a selected memory cell, after a bit line is precharged, to program-verify the memory cell in a nonvolatile memory device. A first read evaluation operation for changing a voltage of the bit line is performed. Results of the first read evaluation operation are sensed using a first sensing voltage. A second read evaluation operation for changing the voltage of the bit line is performed again. Results of the second read verify operation are then sensed using the first sensing voltage.