To solve the problems of becoming a factor of cost increase due to requiring a countermeasure such as increasing strength of concrete and enlarging a pile diameter by taking into consideration reduction in strength by a cross-sectional loss, and worsening heat exchange efficiency by interposing the concrete for constituting a foundation pile between an underground part and a heat exchange pipe, in arranging the heat exchange pipe inside the foundation pile, in a system for exchanging heat with the underground part by using the foundation pile as a structure.

Here, this invention proposes an installation mechanism of the heat exchange pipe for supporting the heat exchange pipe 5 in a cubic spiral shape on the outer peripheral side of the foundation pipe so as to be positioned in a void of a design pile diameter of the foundation pile and an excavation hole.