1. A system operation predicting apparatus capable of predicting the operation of a system in which a plurality of individual processing elements are operated in parallel, said system operation predicting apparatus comprising: input means for inputting element information about all operating states generated in each of the processing elements, all transitions occurring between the operating states, and restrictions on the transitions imposed by operating states or transitions in other processing elements in a graphic language; element information storage means for storing the element information inputted by said input means; present system state storage means for storing a combination of present states in each of the processing elements; next system state candidate generating means for generating all combinations of a next state in at least one of the processing elements and the present state in the other processing elements on the basis of the present system state and information on the transitions stored in said element information storage means, as next system state candidates; determination means for determining, for each next system state candidate, whether a system transition between the present system state and the next system state candidate is permitted with respect to the transition in the processing element contained in the system transition on the basis of information on restrictions stored in said element information storage means; system state information storage means for storing the system transition determined to be permitted and the next system state corresponding thereto; control means for updating the present system state stored in said present system state storage means by the next system state and controlling said next system state candidate generating means to generate a new next system state candidate on the basis of the updated present system state; and preparing means for preparing a states diagram illustrating the system states and the transitions stored in said system state information storage means.