To provide a sufficient loading stability, and ship more kinds of parts at the same time by a method wherein parts of the same kind are gathered as a group, and at the same time, the loading priority of part groups is determined, and also, the stable loading direction information for the part group is incorporated to perform an additional loading process.

Each characteristic data of parts and the container is input, and the data is stored in a part-container characteristic memory means 16, and at the same time, the data is output to an optimum part loading operation means 14 when required. In the optimum part-loading operation means 14, parts to be loaded in each housing case are temporarily allotted within a range which does not exceed the housing case loading volume, in the order from the earliest delivery due date, and also gathered as a group for the same kind to make a part group. Then, the part groups are arranged with the part weight as the first priority and the part group loading volume as the second priority, and the part group is loaded in the housing case. At the same time, a remaining space shape of the housing case after the loading is calculated, and an additional loading is performed.