A method of operating a nonvolatile memory device includes performing a LSB program operation on memory cells coupled to a selected word line and a word line adjacent to the selected word line; performing a first MSB program operation so that the threshold voltages of the memory cells coupled to the selected word line reach temporary voltages lower than first target voltages; performing a second MSB program operation so that the threshold voltages of the memory cells coupled to the word line adjacent to the selected word line are higher than second target voltages; and performing a third MSB program operation so that the threshold voltages of the memory cells coupled to the selected word line are higher than the first target voltages.