The non-volatile memory device may include one or more main strings each of which may include first and second substrings which may separately include a plurality of memory cell transistors; and a charge supply line which may be configured to provide charges to or block charges from the first and second substrings of each of the main strings, wherein each of the main strings may include a first ground selection transistor which may be connected to the first substring; a first substring selection transistor which may be connected to the first ground selection transistor; a second ground selection transistor which may be connected to the second substring; and a second substring selection transistor which may be connected to the second ground selection transistor. A method of programming a target cell of the memory device includes activating selection transistors connected to a main string and substring of the target cell.