A non-volatile memory device is provided. The non-volatile memory device includes a cell string including a plurality of non-volatile memory cells; and an operation control block configured to supply a program voltage to a word line connected to a selected non-volatile memory cell among the plurality of non-volatile memory cells during a program operation, configured to supply a first negative voltage to the word line during a detrapping operation, and configured to supply a second negative voltage as a verify voltage to the word line during a program verify operation.