A method of programming a nonvolatile memory device includes performing a first LSB program operation on memory cells coupled to a selected word line in order to store least significant bit (LSB) data in the memory cells, performing a first most significant bit (MSB) program operation on the memory cells coupled to the selected word line, such that threshold voltages of the memory cells rise up to a temporary target voltage less than a target voltage, performing a second most significant bit (MSB) program operation on memory cells coupled to a neighboring word line neighboring the selected word line in order to store most significant bit (MSB) data in the corresponding memory cells, and performing a third most significant bit (MSB) program operation, after performing the second most significant bit (MSB) program operation, on the memory cells on which the first most significant bit (MSB) program operation has been performed, such that the threshold voltages of the memory cells coupled to the selected word line become higher than the target voltage.