PURPOSE: To enable the operator of the system to support the fault diagnosis of the system by displaying the three-dimensional solid model and cross section of faulty equipment in a schematic flow diagram displayed as a result of fault diagnosis.

CONSTITUTION: A schematic flow diagram data storing means 40 stores various kinds of schematic flow diagram data of a plant to be monitored and diagnosed and a computer aided design (CAD) data storing means 50 stores the CAD data of major equipment constituting the plant. A solid model displaying data means 60 converts data read from the means 50 into data which can display the three-dimensional solid model and cross section of equipment. A displaying means 70 displays and outputs data outputted from a parts-related information storing means 30 and the means 40 and 50. An operator-instruction information inputting means 80 inputs information, such as screen coordinates, etc., on the means 70 instructed from the operator of this system. In addition, the displaying means 70 displays restoring information indicating the parts restored from faulty states.