Abstract: For providing a high voltage detector circuit for discriminating whether a voltage supplied to an input terminal (1) is higher or not than a power supply thereof, stably independent of its power supply fluctuation or noises and without problem of gate oxide break because of high voltage; a high voltage detector circuit of the invention comprises: a MOS transistor (P1) with its gate connected to the power supply; a first resistor (R1) connected between a source of the MOS transistor and the input terminal; a second resistor (R2) connected between a drain of the MOS transistor and a ground; and an inverter for outputting inverse logic of a drain voltage of the MOS transistor to an output terminal (OUT).