A control apparatus for an AC rotary machine, which controls an AC rotary machine having a first winding group and a second winding group, comprising: a current detection unit (3, 4) that detects a current flowing through the first winding group and a current flowing through the second winding group; a sum voltage calculation unit that calculates a sum voltage on a rotational two-axis coordinate system on the basis of a sum current, which is a sum of the current of the first winding group and the current of the second winding group, and a current command for the AC rotary machine; a differential voltage calculation unit that calculates a differential voltage on the rotational two-axis coordinate system on the basis of a differential current, which is a difference between the current of the first winding group and the current of the second winding group; a first voltage calculation unit that calculates a voltage command for the first winding group on the basis of a sum of the sum voltage and the differential voltage; a second voltage calculation unit that calculates a voltage command for the second winding group on the basis of a difference between the sum voltage and the differential voltage; and a voltage saturation determination unit that determines whether or not voltage saturation has occurred; characterized in that the voltage saturation determination unit determines whether or not voltage saturation has occurred in the first winding group or the second winding group on the basis of at least one of a voltage and a current relating to the first winding group and the second winding group, and when determination is made that voltage saturation has occurred in the first winding group or the second winding group, generates a voltage saturation determination signal for reducing a gain of at least one axial direction component on the rotational two-axis coordinate system. a current detection unit (3, 4) that detects a current flowing through the first winding group and a current flowing through the second winding group; a sum voltage calculation unit that calculates a sum voltage on a rotational two-axis coordinate system on the basis of a sum current, which is a sum of the current of the first winding group and the current of the second winding group, and a current command for the AC rotary machine; a differential voltage calculation unit that calculates a differential voltage on the rotational two-axis coordinate system on the basis of a differential current, which is a difference between the current of the first winding group and the current of the second winding group; a first voltage calculation unit that calculates a voltage command for the first winding group on the basis of a sum of the sum voltage and the differential voltage; a second voltage calculation unit that calculates a voltage command for the second winding group on the basis of a difference between the sum voltage and the differential voltage; and a voltage saturation determination unit that determines whether or not voltage saturation has occurred; characterized in that the voltage saturation determination unit determines whether or not voltage saturation has occurred in the first winding group or the second winding group on the basis of at least one of a voltage and a current relating to the first winding group and the second winding group, and when determination is made that voltage saturation has occurred in the first winding group or the second winding group, generates a voltage saturation determination signal for reducing a gain of at least one axial direction component on the rotational two-axis coordinate system.