Each of a plurality of process execution portions includes an accumulation portion to accumulate a job in which the first process among processes not yet executed is an in-charge process, and a batch processing portion to execute the in-charge process on combination data including one or more data on condition that a total process volume becomes equal to or greater than a lower limit value predetermined for the in-charge process. The batch processing portion includes a determination portion to determine whether there exists a job having a previous process now being executed, a first delay portion to delay start of the in-charge process until a prescribed time has elapsed since the total process volume becomes equal to or greater than the lower limit value, and a second delay portion to delay start of the in-charge process until a job determined that the previous process is now being executed is accumulated.