An information processing device sends task unit indicator information for a set of task units having an assigned execution sequence to a robot control device and numerical control device which are work performing elements. A work performing element that can execute the first task unit sends back a notification for executability. The information processing device selects one of the work performing elements which has output a notification for executability, and issues an execution command to same. After execution, the task unit indicator information, from which the first task unit that has been executed is deleted, is returned to the information processing device. The information processing device then sends this task unit indicator information to all of the work performing elements. Thereafter, this processing is repeated until task units disappear in the task unit indicator information.