Embodiments relate to a level shifter which uses a single voltage source, has an excellent operation characteristic even when a difference between a low voltage and a high voltage is large, and can be easily designed. Embodiments relate to a level shifter for shifting a voltage level between an input terminal connected to a circuit block which operates by a low voltage source and an output terminal connected to a circuit block which operates by a high voltage source. In embodiments, the level shifter may include a pull-up PMOS and a pull-down NMOS, both of which are connected between the high voltage source and ground in the form of an inverter and have an output node connected to the output terminal. The level shifter may include a control node which is connected to inputs of the pull-up and pull-down NMOS in the form of the inverter. The level shifter may have an input gate for connecting the control node to the high voltage source or ground according to a voltage level of the input terminal. The level shifter may also include a first feedback chain which is connected between the control node and the input gate and disconnects the input gate and the high voltage source when the voltage level of the input terminal is high and the input gate connects the control node to ground.