To quicken convergence to an optimum solution by converting respective operation bodies inside the two or more same temporary schedules of the plural pieces of the temporary schedules to changed respective operation bodies by a search means.

The search means decomposes one temporary schedule GN into temporary allocation patterns Rg1-Rg4 for the number of the operation bodies for indicating the presence/absence of allocation to the respective operations of respective non-allocated operation groups and the respective operation bodies. Inside the temporary allocation patterns Rg1-Rg4, allocation presence/absence data are changed between the different temporary allocation patterns or inside the same temporary allocation pattern, the changed temporary allocation pattern groups Rg'1, Rg'2, Rg3 and Rg4 are compiled to one temporary schedule GN and it is executed to one or two or more of the plural pieces of the temporary schedules. Thus, the convergence to the optimum solution is quickened and efficient search is realized.