3. A fault diagnosis method for detecting a cause of the fault occurring in an object executing a plurality of processes comprising the steps of: holding rules for first interactions between an attribute of a part and another attribute of the part or an attribute of a child part of the part according to each part of the object, in a part data base; holding an execution order for the plurality of processes, a knowledge of a relationship between a part used in each process and another part, and rules for second interactions between attributes of a medium and a part used in the operation in each process as a process model in a process model memory; and performing the fault diagnosis by determining fault statuses of attributes of parts and media after each of the processes, said fault statuses being candidates for causes of effecting statuses of attributes corresponding to the fault in a following process, sequentially in reverse order of the execution order held in the process model memory, using model-based reasoning by referring to the first and the second interaction relationships, the knowledge of the relationship between the part used in each process and the another part and statuses of attributes of the parts and the media determined in the following process.
3. A fault diagnosis method for detecting a cause of the fault occurring in an object executing a plurality of processes comprising the steps of: holding rules for first interactions between an attribute of a part and another attribute of the part or an attribute of a child part of the part according to each part of the object, in a part data base; holding an execution order for the plurality of processes, a knowledge of a relationship between a part used in each process and another part, and rules for second interactions between attributes of a medium and a part used in the operation in each process as a process model in a process model memory; and performing the fault diagnosis by determining fault statuses of attributes of parts and media after each of the processes, said fault statuses being candidates for causes of effecting statuses of attributes corresponding to the fault in a following process, sequentially in reverse order of the execution order held in the process model memory, using model-based reasoning by referring to the first and the second interaction relationships, the knowledge of the relationship between the part used in each process and the another part and statuses of attributes of the parts and the media determined in the following process. 4. A fault diagnosis method according to claim 3, wherein the fault diagnosis is executed using a tree which expresses relationships between causes and effects of faults and which has been created on a basis of both the attributes of the parts and the attributes of the media.