In a multiprocessor system, in general, a processor assigned with a larger amount of tasks is apt to perform a larger amount of communication with other processors assigned with tasks, than a processor assigned with a smaller amount of tasks. Thus in order for each processor to be able to perform the routing process efficiently, tasks are assigned such that, when there are a first processor and a second processor, the number of processors each assigned with one or more tasks and directly connected with the second processor being smaller than the number of processors each assigned with one or more tasks and directly connected with the first processor, the amount of tasks assigned to the first processor is equal to or larger than the amount of tasks assigned to the second processor.