To provide an air conditioning system using geothermal heat and solar heat suitable for a detached house and easily and inexpensively usable by anyone.

The outside air is introduced to a vent pipe 1 buried in the ground, and in summer, the air cooled by heat exchange with geothermal heat is introduced into the house through an indoor-side outlet port 7 of the vent pipe 1. In winter, the air introduced to the vent pipe 1 buried in the ground is heat-exchanged with geothermal heat, and the warmed air is further heated within a solar heat collection box 3 provided on a roof, and released into the house. According to this, the inside of the house can be made to a comfortable space throughout the year by use of cost free energy regardless of summer time or winter time.