A voltage regulator as a stable power supply to internal circuits in a semiconductor memory device is provided. This regulator includes a comparing unit, a first driver transistor, a feedback unit, an auxiliary control unit, a first switch, a second switch, and a second driver transistor. The comparing unit compares a reference voltage with a feedback signal to control the first driver transistor and maintain the internal power supply at a stable level. The second driver transistor, controlled by the first and second switches responsive to a trigger signal corresponding abrupt current consumptions and the auxiliary control unit responsive to the comparing result, supplies sufficient and appropriate current to the internal circuits and prevents the internal power supply from excessive overshoot and drop-out.