An internal voltage generator circuit is disclosed. The internal voltage generator circuit includes a comparator configured to compare a first voltage with a reference voltage and to output a comparison signal. The circuit further includes an internal voltage driver configured to receive an external voltage and the comparison signal and to output an internal voltage at an internal voltage output terminal, based on the comparison signal. The circuit further includes a voltage divider circuit including first and second resistor units and a first voltage output terminal between the first and second resistor units, configured to receive the internal voltage, and configured to output the first voltage based on the resistance values of the first and second resistor units, the first and second resistor units connected in series, and the first voltage being output through the first voltage output terminal. The circuit further includes a control signal generator circuit configured to generate at least one resistor control signal for controlling the resistance value of the first resistor unit and at least one resistor control signal for controlling the resistance value of the second resistor unit, on the basis of the comparison signal and a precharge command.