To charge a battery by a generated voltage of the generator of a vehicle keeping the battery charged level appropriately.

The control device of the generator of a vehicle comprises a revolution detector 21 which detects the generating revolutions of a rotating mechanism in a generator 11, a generated voltage regulator 25 which regulates the generated voltage of the generator 11 and an operation unit 27 to control the generated voltage regulator 25 so that the generated voltage 11 is lowered than predetermined in the case that the revolutions detected by the revolution detector 21 becomes larger than the first predetermined revolutions in order to control the generator 11 which generates the power to be supplied to a battery 2 mounted in vehicles.