A control device for an AC rotating machine includes: switching control means for controlling inverters and motor relays 15; and abnormality detection means for detecting an abnormality in each system and outputting a result of the detection to the switching control means. When the abnormality detection means detects an abnormality in at least one of the systems, the switching control means causes the motor relay to block a circuit between windings and the inverter in the system in which the abnormality has been detected, and continues normal control in a system other than the system in which the abnormality has been detected.