PURPOSE: To average the production quantity during a specific period, by instructing the number of necessary jigs when the number of the jigs is short, and making a production number for a short period to a production number in a period designated at random.

CONSTITUTION: In order to prepare a production plan for each one day, a long period production plan formed beforehand is obtained (S1). After the long period production plan is obtained, it is set whether the production is carried out or not by applying the part several days in advance of the long period plan to the furture (S2). Then, it is decided whether there is an advancing production or not (S3). Then, it is decided whether the jig is exchanged or not (S9).When it is necessary to exchange the jig in reference to the result of the jig exchange decision (S12), an instruction to exchange the jigs in the order of changing according to the changing order is output (S13). And the changing order for one day (for production amount to-day) is displayed (S14). Consequently, the exchange of jigs suitable for the production plan is carried out, a production for each one day is averaged, and the production efficiency is improved.