A design support system has been developed for constructing VR-based training environment for machine maintenance work without any expertise and programming effort on VR. Using the developed system, users can easily construct various training environments under GUI environment. It was verified through some experiments that the developed system could reduce the working hours remarkably and that novice users who had no prior knowledge on the system could construct a training environment successfully after a few hours of tutorial on the system. In this paper, the basic concept of the system, the way to model the state transition of objects by Petri net and experimental results are described.