A job assignment apparatus of an automatic material-handling apparatus to calculate an initial optimum solution based on a cost table configured by the job assignment, and to calculate a single optimum solution based on the cost table converted by statistical data. The Hungarian algorithm is stored in a tool storage unit to calculate the optimum solution. A statistical-data calculator calculates statistical data to convert costs of the initial cost table into other costs. The cost-table converter converts the costs of the initial cost table based on the calculated statistical data.