Abstract: A flash memory device includes a cell array and a control circuit. The cell array includes a first NAND string having first flash memory cells having control gates respectively connected to word lines, and a first bit line selection switch connecting the first flash memory cells to a first bit line according to a control of a first string selection line. The control circuit controls a first erase operation for erasing a selected flash memory cell. The control circuit controls a voltage difference between the first bit line and the first string selection line to have a first value for generating gate induced drain leakage (GIDL) at the first bit line selection switch, and controls a voltage of a control gate of the selected flash memory cell and a voltage of a control gate of an unselected flash memory cell to be different from each other.