A semiconductor device according to an embodiment may include cell strings including a plurality of memory cells coupled between bit lines and a source line and coupled to word lines, a peripheral circuit suitable for programming selected memory cells coupled to a selected word line among the word lines by applying a program voltage to the selected word line, and applying one or more pass voltages to unselected word lines, and a control circuit suitable for controlling the peripheral circuit to temporarily float the unselected word lines while the selected memory cells are programmed.