PURPOSE: To attain the change of the object class definition during a network control operation by generating the instance of the corresponding class with updating of or reference to a class information table based on the information obtained in terms of a list.

CONSTITUTION: In regard of the complicated processing where the succeeded characteristic is obtained, an updating class information table is prepared with the batch processing via a succession tree generating/updating means 1 and a class information table producing/updating means 2. The temporary exclusive control is carried out via a lock semaphore access means 4 and based on the information obtained in terms of a list. Thus the class information table is updated. Therefore even an instance generating means 3 required for execution of the real time processing can update the characteristic of a designated object class identifier to the latest object class defining information just with the temporary exclusive control applying the means 4 in terms of a list. Thus the definition of an object class can be changed during a network control operation.