To provide an economical and efficient method for posting working staff without adjusting the amount of production.

In this method for posting working staff corresponding to the workload of each working process in manufacturing products through a plurality of operation processes according to a production plan, the workload in each operation process is simulated from the production plan, and whether the workload in each operation process can be carried out by the working staff preliminarily set in each operation process is simulated. When it is judged that the workload in a first working process 16 among those working processes cannot be carried out from the simulation, the working staff in a second working process 14 whose workload is judged to be realizable among those working processes are reduced, and the reduced working staff are added to the first working process 16.