To control a small drooping current by increasing an inductance by using an externally wound solenoid coil, without increasing the number of turns of an output winding and a control winding.

In the control apparatus for constant voltage in a permanent-magnet generator uses a permanent-magnet member as a rotor and includes a stator having a winding on the outside of the rotor. The control apparatus includes an output-side winding, including the output windings 10 and 11 wound in the stator, and output-winding side solenoid coils 141 arranged outside the stator, and control-side solenoid coils 142, that connected in series to the output-side winding and arranged outside the stator. The control apparatus, further, includes a control apparatus 18 controlling a control switch 12, in response to detecting signals from a sensor 16 detecting the voltages generated by the control switch 12 for allowing a portion of the currents generated in the output windings 10 and 11 disposed among the output-side windings and the control-side solenoid coils 142 for making them flow through the control-side solenoid coils 142 and the output windings 10 and 11.