In a power-generator control apparatus installed in a power-generator designed to generate an output voltage at an output terminal thereof, a regulating unit regulates the output voltage so that the regulated output voltage is equivalent to a first target value. When a periodic signal with a predetermined frequency is applied from the outside of the power-generator to the output terminal thereof to be superimposed on the output voltage, a regulated voltage changing unit operatively connected to the regulating unit receives the periodic signal, and compares the frequency of the received periodic signal with a predetermined threshold frequency. The regulated voltage changing unit changes the first target value of the regulated output voltage to a second target value upon the frequency of the received periodic signal being higher than the predetermined threshold frequency.