To provide an air conditioning system favorable to the environment with a simple composition and easy construction, capable of efficiently using ground heat in air conditioning of a building.

A plurality of hollow bearing piles 210 made of steel pipes with closed tips are embedded, and top parts are communicated and connected with a first main pipe 430 communicated and connected with an outdoor inlet 31 of a blower 300. Flexible inner pipes 420 are respectively inserted in a state of extending from upper ends of the embedded the plurality of bearing piles 210 to an exterior with axial one ends opened in lower end neighborhoods of the hollow bearing piles 210. Other extended ends of the inner pipes 420 are respectively communicated and connected with a second main pipe 440 communicated and connected with an outdoor outlet 312 of the blower 300. Air in the bearing pile 210 having favorably exchanged heat with the ground can be directly used in air-conditioning of a room, and favorable air-conditioning can be provided by using a foundation having positive bearing capacity of a building by a simple composition and easy construction.