A statistically added point calculation unit of the present invention statistically adds a point to a part related to a content of an anomaly in error information received by an error information receiving unit, and sets the added point in an added point table. A suspected place identifying unit refers to the added point table, and if the statistically added point of a target of determination has exceeded a threshold, the suspected place identifying unit identifies the target of the determination as a suspected place. If the configuration information table is referred to and a target of this process is a maintenance part at the suspected place, the suspected place identifying unit compares an initial value, for example, by means of the threshold which has been doubled. Furthermore, the suspected place identifying unit identifies a part having the statistically added point which is the next highest, as a second suspected place. A part isolation processing unit isolates the part at the suspected place. A configuration information management unit sets a second suspected place flag at the corresponding part in the configuration information table.