Provided are a low-cost control device and the like for a vehicle generator-motor for minimizing the number of current sensors and the like, and estimating an output torque and a current consumption during drive of the generator-motor. The output torque and the current consumption during the drive of the generator-motor are estimated based on a field current, an rpm, a DC voltage, and a phase of an AC voltage to be supplied of the generator-motor, without providing a current sensor for detecting an input current from a power supply to an inverter device of the generator-motor, and a current sensor for detecting an output current from the inverter device to an armature winding of a rotary electric machine.