Large-scale table format data on a common memory is sorted in parallel by a plurality of processors. A record to be processed is divided and assigned at first to the processors. Next, each processor counts the number of local appearances of item value numbers related to the record to be processed. Next, the number of local appearances of the item value numbers counted at the processors is converted into the global accumulation of item value numbers, i.e., the accumulation to be commonly used between the processors. Finally, each processor utilizes the global accumulation as a pointer to change the order of the assigned records.