A level shifter for a flat panel display device includes: first and second transistors that are different type transistors and serially coupled between first and second power supplies, the second power supply for supplying a lower voltage power than the first power supply; a first capacitor between gate electrodes of the first and second transistors; an input line for a first input signal coupled to the gate electrode of the first or second transistor; a third transistor between a second electrode of the first capacitor and a third power supply, the third transistor having a gate electrode coupled to an input line of a second input signal; and a fourth transistor between the second electrode of the first capacitor and the third transistor, the fourth transistor having first and gate electrodes that are coupled to the second electrode of the first capacitor, such that the fourth transistor is diode-connected.