PURPOSE:To minimize interruption of a processing, by own judging of each processor for disagreement in synchronism and judging the result by an other processor, in the multiprocessor synchronizing system. CONSTITUTION:In the load scattering multiprocessor exchange system, if the result of collection between processors TKPi0 31 and TKPi1 32 during synchronizing operation shows the detection of disagreement, interruption is made to the processors TKPi0 31 and TKPi1 32 and maintenance call processor MCP 5. TkPiO 31 and TKPi1 32 hold the present status, the self disgnostic program is executed,the result is set to the specific address of memory and stopped. MCP5 sets the timing by the execution time of the self diagnostic program, and the self diagnostic result set address of TKPi0 31 and TKOi1 32 is read in to discriminate the failure. After the discrimination, the normal processor is restarted after the time of interruption.