1. A multiprocessor system having a plurality of processors to which control to be performed is allocated, comprising: an abnormal operation detecting unit which detects an abnormal operation that has occurred in a specific processor of the plural processors; an instructing unit to change a specific control allocated to the specific processor to be performed in a substitute processor which is one of the processors other than the specific processor based on a result detected by the abnormal operation detecting unit; and an abnormal operation diagnosing unit which diagnoses whether the abnormal operation occurs in hardware of the specific processor; wherein if the abnormal operation is detected in the specific processor by the abnormal operation detecting unit, the specific control is performed by the substitute processor, and if the abnormal operation is diagnosed to not be in the hardware of the specific processor by the abnormal operation diagnosing unit, a previous control, which has been allocated to the substitute processor, is allocated to be performed by the specific processor, and wherein the instructing unit changes an OS and an application program to be executed on the OS, and wherein the instructing unit changes an OS for vehicle control allocated to the specific processor to one of the processors to which an OS for information control has been allocated.