Abstract: In a voltage regulator for charger/generator comprising a switching element, connected between a battery and a field winding of a generator adapted to charge the battery, for switching on and off an exciting current flowing through the field winding and a voltage detector responsive to voltage of the battery to control the operation of the switching element, there are provided an oscillator for generating an oscillation signal of a desired duty ratio, an initial excitation signal generator circuit having a plurality of stages of frequency dividers for dividing the frequency of the oscillation signal generated from the oscillator and combining together frequency division signals of the frequency dividers to produce a synthesized output signal of a desired duty ratio, a booster for boosting and rectifying an AC signal containing the oscillation signal of the oscillator and a signal which is opposite in phase to the oscillation signal to produce a boosted output signal, and excitation control means being operati