An electrical angle estimation section calculates an estimative electrical angle on the basis of an inductive voltage generated in a motor, and obtains an estimative electrical angle by correcting the estimative electrical angle by an electrical angle correction amount. On the basis of a detection value which represents the difference in electrical angle between the q-axis and the δ-axis calculated by an electrical-angle-error detection section, an electrical-angle-correction-amount computation section calculates an electrical angle correction amount such that the electrical angle of the δ-axis falls within a prescribed angular range, which lags behind the q-axis in terms of electrical angle. Thus, when sensorless control is performed, a phenomenon in which the motor loses synchronism can be restrained.