A level shifter includes; a level conversion unit which receives a first input signal and a second input signal, wherein the second input signal is an inversion of the first input signal, and generates a first output signal having substantially a same phase of the first input signal and a voltage which is higher than the first input signal and a second output signal having substantially a same phase as the first input signal and a voltage which is lower than the first input signal; and wherein the level shifter further includes an amplifying unit which receives the first and second output signals and generates a third output signal having substantially a same phase as the first input signal and an amplitude which is greater than the first input signal.