PURPOSE: To omit the necessity to always monitor the restart of a processor by loading the patch data into the memory of a relevant processor and restarting this processor if a processor requiring the application of a patch is included among those processors that undergone the IPL (initial program loading).

CONSTITUTION: When a desired patch to be applied to a memory only is pro duced, a maintenance console 6 rewrites the memory of the corresponding proces sor based on a command. Furthermore, the patch is registered into a patch control table 8. If an IPL control processor 1 detects a fault of a processor 3, for example, the processor 1 applies the IPL to the processor 3 and then refers to the table 8 after the end of the IPL. Thus, the processor 1 loads the patch data to the memory of the relevant processor and restarts this processor when a processor requiring the application of a patch is included among those processors that undergone the IPL. Thus, it is possible to always monitor the restart of the processor.