PURPOSE: To prevent such an inconvenient case where the sewing products are not in time for the time limit of delivery by calculating accurately the detailed load caused in a production line end operating the production line with high efficiency.

CONSTITUTION: An electronic controller 3 works on the basis of a CPU 1. The CPU 1 is connected to an input device 9 like a keyboard, a mouse, etc., a display device 11 which shows the load calculation result, etc., an external storage 13 which stores the various data on the order reception information, the process analysis information, the process formation information, etc., and a printer 15 which outputs the load calculation result respectively via the common buses 17 and an input/output port 19. Then the CPU 1 reads the necessary data out of the storage 13 in regard of the order reception information included in a range designated by the device 9 and calculates the detailed load caused in a production line.