A nonvolatile memory device includes a memory cell array, a voltage generator and a control logic circuit for programming a selected memory cell of the memory cell array to a selected word line into a first program state by controlling the voltage generator and a verify operation on the memory cell array. The control logic circuit controls a first word line voltage applied to an adjacent word line not to be programmed in the verify operation to be different from a read voltage level of a read voltage applied in a read operation of the nonvolatile memory and controls a bit line voltage applied to a bit line in the read operation. The control logic circuit controls the voltage generator to apply a plurality of different and decreasing verify voltages to the selected word line in the verify operation.