A control apparatus is provided for restraining fluctuations in the output due to disturbance and the like to achieve high stability and control accuracy for the output of a control object. The control apparatus calculates a virtual interference input applied to the control object in order to generate a virtual interfering force for holding the detected output of the control object at a predetermined value. The control apparatus assumes the control object applied with the virtual interference input as an enlarged control object, and calculates a virtual control input applied to the enlarged control object based on a predetermined response specifying control algorithm such that the output of the enlarged control object converges to a set target value.