To provide a steel house with excellent energy saving and dew condensation preventing properties.

In this steel house, a main skeleton is formed by using a square steel pipe for a column and a lightweight H-steel for a horizontal beam. The outer surface of the main skeleton is surrounded by an insulation material, and the temperature and humidity controlled air is circulated on the inside of the insulating material. After the outside air is passed to a heat exchanger of double tube structure buried in the ground, the circulation air is passed through a cobble stone layer stacked under the floor of the steel house to control the temperature and the humidity.