1. A control apparatus for controlling an object that is modeled by a model equation that uses a plurality of model parameters, an input of the object and an output of the object, the plurality of model parameters including at least one first model parameter and at least one second model parameter, the model equation including at least one term that uses the first model parameter and at least one term that uses the second model parameter, comprising: a memory for storing the at least one predefined first model parameter; a partial model parameter identifier for recursively identifying the at least one second parameter based on an output from the object and an input into the object; and a controller for using the first model parameter and the at least one second model parameter identified by the partial model parameter identifier to determine an input into the object so that the output from the object converges to a desired value, the partial model parameter identifier constructing a virtual plant including the object and a component that is represented by the term using the first model parameter in the model equation, and modeling the virtual plant by a virtual model equation that uses the second model parameter and does not use the first model parameter, and the partial model parameter identifier further identifying the second model parameter so that an output from the virtual plant converges to an output of the model represented by the virtual model equation of the virtual plant.