PURPOSE: To improve the mastery degree in plant driving operation of an operator by judging the mastery degree in the plant driving operation of the operator, and displaying the judged result of the mastery degree on a display means.

CONSTITUTION: After an operator operates a selecting key and a master key provided on an operating device 5 to time-serially process process-information 15 issued from a control device 1 in a monitor 2, the above processed information is given to a record regenerating device 3 as a plant operation result information 21. The result of judgement which is executed about the mastery degree in the plant driving operation of the operator on a rule base and the information 21 through the inference mechanism of the record regenerating device 3 is displayed on a display device 4 as a plant operation result display information 22. Thus the mastery degree in the plant driving operation of the operator can be judged and improved.