Metal products are bulky or heavy cargo, and most of them are transported by sea. In the case of cargo transportation through the sea, there are many cases where dew condensation occurs due to high humidity and temperature changes inside the container during the transportation period, which causes corrosion (rust) on metal products, which in many cases raises a claim. In this paper, in order to prevent corrosion (rust), the relative humidity inside the container is maintained below 50%, which does not cause metal corrosion, by using a container dehumidifier, heating device, and air circulation device, and the temperature difference between the room temperature and the metal surface. A device for maintaining 2~4℃ was fabricated and its validity was confirmed through experiments and CFD.