The control apparatus controls a controlled variable of the electric rotating machine by manipulating an output voltage of a power converter circuit including switching elements operated to connect positive and negative terminals of a DC power source to corresponding terminals of the electric rotating machine. The control apparatus includes a prediction section configured to predict the controlled variable for each of a plurality of cases where the power converter circuit is set in a corresponding one of a plurality of predetermined operating states, a feedforward control section configured to set a command value of the controlled variable in accordance with the voltage of the DC power source and the electrical angular velocity of the electric rotating machine, and a manipulation section configured to select one of the predetermined operating states depending on a result of evaluation by an evaluation function receiving the predicted controlled variable and the command value.