PROBLEM TO BE SOLVED: To compute a variance in a predetermined output of a model to be controlled occurring when a predetermined control parameter is inputted to the model to be controlled, and contribute to stabilization of the predetermined output.SOLUTION: A data processing unit M4 for plant control is employed in a control system M3 that controls a plant M1 to be controlled. The data processing unit includes a physical model parameter estimation unit M41 that estimates a physical model parameter of the model to be controlled of a plant and a variance in the physical model parameter on the basis of running data of the plant, and an output variance arithmetic unit M45 that computes a variance in a predetermined output of the model to be controlled, which occurs when a selected predetermined control parameter is inputted to a model M43 to be controlled, on the basis of the variance in the physical model parameter, and outputs a result of the computation.SELECTED DRAWING: Figure 1
