In a vehicle voltage control apparatus which regulates the output voltage of the vehicle electric generator and which receives an external control signal for lowering the regulated voltage value, from an external apparatus such as the engine ECU during engine starting, a circuit detects the occurrence of engine starting based upon the frequency of an AC voltage produced by the generator or upon the level of output voltage produced by the generator. The regulated voltage value is set to a substantially low level, predetermined for use during engine starting, only while the control signal is being received concurrent with engine starting also being detected.