To provide a building using geothermal heat efficiently collecting geothermal heat without impairing safety of the building.

Air circulating steel pipes 30 forming a U-shaped air passage are buried in soil cement columns 62 buried in the ground, and the plurality of air circulating steel pipes 30 are connected by connection pipes 80 on a mat foundation 70 to form a serial air passage. The temperature of air that enters from an air introducing end 81 of the serial air passage becomes substantially the same as that in the ground while flowing through the U-shaped air passage of the air circulating steel pipes 30, and the air is blown out into the building from an air discharge end 82. By using the soil cement columns 62 reinforcing the support ground of the building, the building using the geothermal heat can be built safely.