The trend of cold insulation box is sewn products. However, they are in face of a problem that the demand of box far exceeds the supply, because it requires lead time to sewing. Therefore, an immediate solution was required, due to the problem was remarkable in the large-sized box, specifically. And it was realized that the foldable box made from corrugated plastic board and foamed polypropylene without sewing, with the reduction of material cost and improvement of workability.