PURPOSE: To make effective countermeasure for abnormalities by a method wherein the occurrence status of abnormalities per unit is displayed by measuring both of the occurrence frequency and recovering time per abnormality code.

CONSTITUTION: An abnormality detecting.encoding means 1 detects any abnormality requirement from output signals from sensors, etc., fitted to respective units simultaneously converting into abnormality corresponding to respective abnormality requirements for transmitting to an abnormality occurrence frequency.correcting time counting means 2. As to the transmitted respective codes, the occurrence frequency.correcting time are counted by the abnormality occurrence frequency.correcting time counting means 2 to be stored in an abnormality occurrence frequency.correcting time storing means 3. Next, scope displaying means 5 reads out the occurrence frequency.correcting time per abnormality code from the abnormality occurrence frequency.correcting time storing means 3 to be classified per unit by an abnormality code/unit retrieving table 4 so as to sort per unit or count the total amount for displaying them corresponding to the mode of selected scope.