Abstract: To predict a future work status, a variation amount in working efficiency set according to progress of a work regarding the workload and a variation amount in a work resource are considered, and the working efficiency is compensated according compensation of a work resource amount. Data of variation patterns of the working efficiency and the number of workers are previously defined and stored. A variation pattern for each work is selected from the variation pattern data on the basis of a work schedule data stored in the work schedule data storing section. Variation of the workload resource, the workload, and the working efficiency are stored. The prediction result is displayed. Upon excess and lack in the prediction workload over the scheduled workload in a period may be transferred from that period to the next period and from the next to that period, respectively.