PURPOSE: To improve the work efficiency of a patrolman at patrol and inspection and shorten the inspection and location time of abnormality by diagnosing the sign of abnormality of equipment, based on plant information, and displaying the figure of the abnormal section in case that it is judged abnormal as a result of diagnosis.

CONSTITUTION: The information of a plant 1 is inputted through a plant information input means 21, and it is stored in a plant operation state data base DB1 by a plant operation state accumulation managing means 22. Next, an abnormality sign diagnosing means 23 judges the abnormality sign, based on data base DB1 and abnormality sign judgment criteria DB2. When abnormality sign is judged to be recognized as a result of diagnosis, an abnormal-state inspection item check-list output means 24 outputs a checklist of inspection items at abnormality to output equipment O1, based on abnormal-state inspection item data base DB3. Moreover, an abnormality sign location figure output means 25 outputs an equipment figure where an abnormality sign location is marked to output equipment O1, based on equipment drawing information data base DB5.