A control device controlling a motor-driven four wheel drive vehicle, where either of front wheels and rear wheels are driven by an engine and the others are driven by an AC motor, is provided with an electric power generator driven by an engine to generate first three-phase AC power, a rectifier rectifying the first three-phase AC power, generated by the electric power generator, to second DC power and supplying the second DC power to a neutral point of the AC motor; and a first step-up and step-down inverter stepping up and converting the second DC power, supplied through the neutral point, to third three-phase AC power. The AC motor is rotationally driven by application of the third three-phase AC power from the first step-up and step-down inverter.