A control apparatus for an alternating-current motor that is driven by an inverter includes a rectangular wave voltage control portion that generates a control command of the inverter such that rectangular wave voltage that has been phase-controlled to make the alternating-current motor operate according to a torque command value is applied to the alternating-current motor; and a phase change control portion that controls a change in the phase to maintain the center of a flux linkage vector locus indicative of a change in a flux linkage of the alternating-current motor before and after a change in the phase of the rectangular wave voltage.