A regulator included in a high voltage generator for supplying a high voltage to a semiconductor memory device is disclosed. The regulator includes a voltage dividing circuit configured to divide an output voltage of a charge pump, a comparing circuit configured to compare a reference voltage with a divided voltage by the voltage dividing circuit, a regulator driving circuit configured to couple selectively the voltage dividing circuit to a ground, and a high voltage discharging circuit configured to discharge the divided voltage applied to the comparing circuit when supply of a power supply voltage is stopped.