A level shifter capable of high speed operation and a high-speed level shifting method. The level shifter includes a pull-down switching unit configured to selectively connect a first node and a second node with a first power supply (ground) voltage in response to a first switching signal and a (complementary) second switching signal, a pull-up switching unit connected between the first node and the second node and configured to connect the first node with a second power supply voltage in response to the voltage level of the second node and to connect the second node with the second power supply voltage in response to the voltage level of the first node, and a internodal switch configured to selectively connect the first node with the second node in response to a control signal. Due to the switching operation and resistance of the internodal switch, the level shifter can reduce power consumption and perform high speed level-shifting operation.