1. A simulation support method comprising: converting a subject block diagram model using a generated operation interface, wherein the subject block diagram model represents a subject system to be simulated, to a model for parallel computation, in which a plurality of subsystem models are connected to each other, wherein the plurality of subsystem models correspond to a plurality of processes in one step, and the processes repeatedly run in parallel in a cluster computer; synchronizing data in a parallel execution environment by inserting dummy blocks in the subject model using the generated operation interface; editing a simulation program for parallel computation, based on the model for parallel computation that is the subject model in which at least the dummy blocks are inserted, wherein the simulation program for parallel computation is used to generate the processes that run in parallel in the cluster computer; and incorporating a communication section into the simulation program for the parallel computation.