In a multi-processor system constituted by a processor such as a CPU and a DSP, in which the processor and the DSP have an external memory and a bus as shared resources and the DSP carries out a process in response to a processing request from the processor, a monitoring step for status of use includes a step of monitoring the status of use of the DSP, and when contention information obtained in the monitoring step for the status of use indicates frequent uses, an altering step for software process appropriately alters a software processing method to be executed, and switches the corresponding process to an equivalent process so that it becomes possible to avoid bus contention, and consequently to prevent a reduction in the processing speed.