PURPOSE: To increase the production efficiency by installing a 1-bit memory pin onto a pallet jig and turning ON only one memory pin when the kind of work is changed and by detecting said turning ON in each process and confirming the next machine group succeedingly.

CONSTITUTION: Production control is performed by an upper rank computer 23. When the counting in a memory pin setting device 24 reaches the production quantity of the present machine group, the computer 23 clears the counting, and an instruction is transmitted so that the memory pin of the next pallet jig 21 is set to ON-state. When the top pallet 21 of the next machine group in which the memory pin is turned ON reaches an automatic machine 25, the top of the next machine group is detected, and the work corresponding to the next machine group is carried out succeedingly. Through this method, the increase of dimension of the equipment, cost up, and increase of processing time can be prevented only by adding the 1-bit information onto the pallet jig 21, and the machine kind replacing work can be lightened.