A detecting means easily detects the abnormality of a generator having a plurality of power supply units. Each of the power supply units includes one of a plurality of output windings L1 to L4, which are wound independently of each other around single iron core, and one of rectifiers 2 to 5 that are provided in correspondence to the output windings and produces an integrated output. Controllers 33 to 35 control the rectifiers such that the output voltage corresponds with a target. A voltage deviation judgment section 37 outputs the abnormal signal when one of the output voltages of the rectifiers 2 to 5 is different from remains. A current deviation judgment section 39 outputs the abnormal signal when one of the output currents of the rectifiers 2 to 5 is different from remains. When the abnormal signal is detected, the outputs of the rectifiers 2 to 5 are stopped.