A regulator for eliminating noises generated by an automotive power generator is composed of a front-end circuit, a semiconductor power element, a resistor, and a capacitor. The front-end circuit includes a plurality of electronic components for offering control signals generated therefrom. The semiconductor power element is electrically connected with a field coil of the power generator, including a gate electrically connected with the front-end circuit for receiving the control signals that switch ON/OFF the gate. The resistor is electrically connected in series between the gate and the front-end circuit. The capacitor includes an end connected with the gate and the other end thereof grounded. Thus, the semiconductor power element can slow down the ON/OFF switching to be further low-cost and simple-circuit for enhanced quality of the output voltage of the power generator.