A level shifter circuit, which includes a Schmitt trigger function, shifts voltage of a high level signal into a low voltage and shifts a signal at an intermediate value of an input voltage. The level shifter circuit includes an input terminal connected to low and high voltage circuits. The low voltage circuit outputs a low drive voltage or ground voltage. The high voltage circuit outputs a high drive voltage or a high reference voltage, which is supplied to an RS latch circuit via a potential adjustment circuit at a level equal to an output potential at the low voltage circuit. The RS latch circuit uses the output of the potential adjustment circuit when the input voltage shifts to a high level and uses the output of the low voltage circuit when the input voltage shifts to a low level.