Solenoid coils not interlinked by magnet flux of a rotor, increase inductance of a control coil system for controlling generated voltage using little current flow to a switch so no increase in windings of a power coil is needed. A generator with rotor having magnets and stator outside the rotor, have winding coil of the stator connected in series to solenoid coil. A power terminal is between the power and control sides of the solenoid coil and a switch controls flow of current from the power coil to the solenoid coil. By controlling ON/OFF condition of the switch disposed on the DC terminal of a rectifier connected to the solenoid coil in series, the generated voltage is controlled to a voltage set in advance, in response to a detection signal from a sensor detecting the voltage.