There is provided a control device configured to control a drive system including a motor and a driven object. The control device includes a controller configured to compute an operation amount, to measure a control amount of the controlled object, to input a measurement signal of the control amount to an inverse model of a model indicating input-output characteristics of the controlled object, and to generate a differential signal between an output of the inverse model and the operation amount; and a filter configured to filter the generated differential signal, and which has frequency characteristics of attenuating a vibrational component which is developed due to mechanical characteristics of the controlled object, from the differential signal. The controller is configured to make a judgment of whether or not a defect has occurred in the controlled object, based on an output of the filter.