A vehicle generator motor has a generator motor that is connected to an internal combustion engine and plural sets of three-phase windings, plural sets of inverter portions connected to the respective sets of the three-phase windings, and a control circuit portion for controlling the inverter portions in accordance with the operation state of the generator motor. When the generator motor operates as a motor and a variation value of an output torque or power generation amount thereof exceeds a predetermined value, the control circuit portion controls the inverter portions so as to stop armature current flowing in at least one set in plural sets of three-phase windings.