It is desirable to support operator activity in abnormal correction of chemical plants. Although fault diagnosis systems have, very fertile grounds for theoretical and. industrial development, multiple possibilities of faults are diagnosed. A countermeasure against one cause might be dangerous when used against another cause. A countermeasure might be effective to multiple causes. Countermeasure planning is necessary to complete fault diagnosis. An operator manipulates one variable while observing one variable in each countermeasure. It resembles the controller configuration of a single loop controller. An algorithm for controller reconfiguration is proposed for the first stage of countermeasure planning.