PURPOSE: To attain the parallel execution of programs in a multi-processor system by controlling the task executing schedule based on the recording time of each task so as to keep the task executing order in the same way as an execution state.

CONSTITUTION: A logging means 5 obtains the recording times for production of each task, the end of each task, the inter-task synchronization, the shared data access, etc., via a timer 3 and stores these times in a buffer 22 of a memory 2. Then an output means 6 writes the recording times stored in the buffer 22 into a log file 4. An input means 7 reads the recording time of each task written into the file 4 into the buffer 22 at regeneration of a multi-tasking program. A control means 8 controls the task executing schedule based on the recording time of each task stored in the buffer 22 so that the task executing order is kept in the same way as an execution state. Thus it is possible to regenerate an executing route exactly same as that set at execution of the multi-tasking program that performed a recording job.