PURPOSE: To improve the continuity and the maintainability of a system function by temporarily changing the monitor time to prevent the output of unnecessary alarm at the time of temporary arrival of the load of a processor at the peak.

CONSTITUTION: In the preprocessing which instructs each processor as the periodical start object to start in accordance with contents of a period register 7, the start status in a register 8 where the status of the current started operation is stored is verified. If the start status of the processor as the start object is 0, a restart command is issued to the processor and the corresponding bit of the start status in the register 8 is set to one. If AND between the monitor condition of a monitor device 14 and the start status is 0, a periodical start command is outputted from a start management device 9 and the monitor timer value is normally set up to a timer register 15 as the result. As the result, alarm output to the external is suppressed.