PURPOSE: To attain consistent check and inspection by converting various diagrams describing the functions of objects into a high level Petri net.

CONSTITUTION: This object directional analysis/design supporting system is provided with a token genereating part 3 for converting the specification of each object in an object diagram 2 into a token, an inter-class dynamic specification converting part 5 for substituting a transition and an event respectively for each object in an object communication diagram 4 and an event to generate a high level Petri net, an intra-class dynamic specification converting part 7 for converting a state diagram 6 into a place, the guard condition of an event into a transition, the event into a transition name, a status transition into an arc, and action at the time of the transition into an arc function, a function specification converting part 9 for substituting a transition and a place respectively for a bubble in a data flow diagram 8 and a flow to generate a high level Petri net, and a Petri net accurate preparation part 10 for substituting a high level Petri net for the transition of the Petri net prepared by the converting part 5.