A method of preventing program-disturbances for a non-volatile semiconductor memory device having a plurality of memory cells of which each includes a selection transistor and a memory transistor coupled in series between a bit-line and a common source-line is provided. First non-selected memory cells that share a first selection-line with a selected memory cell, and second non-selected memory cells that do not share the first selection-line with the selected memory cell are determined when the selected memory cell is selected to be programmed among the memory cells. A negative voltage is applied to second selection-lines that are coupled to the second non-selected memory cells when the selected memory cell is programmed by applying a positive voltage to the first selection-line that is coupled to the selected memory cell.