A model predictive control apparatus constructed in consideration of limit conditions of the process and also suitable for a multi-input/output system and an input device suitable for such a control apparatus are disclosed.The model predictive control apparatus includes an transformation unit for transforming the cost function and the limit condition to a conditional expression only relating to the manipulated variable. A suitable cost function parameter adjustment unit in which robustness is taken into consideration is provided. Alternatively, by designation of a response time constant, a weight corresponding thereto is calculated or determined to carry out evaluation of stability margin.In addition, the input device is adapted to carry out, through a picture on screen, setting or alteration of a predictive model or control parameters, etc. to be inputted, thus to suitably conduct setting while confirming it on the screen.