A level shifter circuit includes a level shifter, an inverter, a first switch circuit and a second switch circuit. The level shifter includes a first transistor, a second transistor, a third transistor and a fourth transistor. The inverter receives an input signal and thus generates an inversion input signal. The first transistor and the second transistor are respectively controlled by the input signal and an output signal to output an inversion output signal. The third transistor and the fourth transistor are respectively controlled by the inversion input signal and the inversion output signal to output an output signal. The first switch circuit is coupled to the level shifter and turns off the fourth transistor when the third transistor is turned on. The second switch circuit is coupled to the level shifter, and turns off the second transistor when the first transistor is turned on.