A control apparatus for an internal combustion engine is provided with: a first determining device configured to determine whether or not the number of revolutions of the internal combustion engine is less than a predetermined number of revolutions and control torque is required for a rotary electric machine; a second determining device configured to determine whether or not required control torque is less than a predetermined threshold value; a first controlling device configured to realize the control state in one arm and to realize the power generation state if the required control torque is less than the predetermined threshold value; a second controlling device configured to realize the control state in both the one arm and the other arm if the required control torque is greater than the predetermined threshold value; and a threshold changing device configured to change the predetermined threshold value to increase with increasing number of revolutions of the internal combustion engine.