To pack products into stable pack-shapes without depending on the ability of a worker, by so packing the products included in a product-shape- group master, categorizing the products into basic-shape patterns and further categorizing them into sizes, and in shipment data that only the products of each group are bundled together.

A packing instruction preparation part 2 categorizes products (product numbers) included in shipment data 7 into corresponding groups based on the registered contents of a product-shape-group master 1, and prepares and outputs a written instruction to pack together only the products of each group. In the product-shape-group master 1, data on shape groups obtained by categorizing various products into basic-shape patterns based on their shapes and also further categorizing the products included in the corresponding basic- shape patterns into groups based on their sizes is registered so as correspond with the product numbers. Thus, because only the products of the similar size and the same shape are packed together, its pack-shape is stable.