To constitute a heat pump system capable of executing underground heat reserve and geothermal utilization to save energy of an air conditioning device and a hot water supply device, as movement of heat quantity of several times to operating energy of the heat pump has limitations, though in a conventional air conditioner (air conditioning device), the heating and cooling is performed by a heat pump while applying the outside air as a heat source to keep a comfortable living room temperature (25 degrees to 28 degrees).

Heat moving efficiency of the heat pump can be improved by reversing the change of the outside air temperature in summer and winter. That is, a problem can be solved by switching the utilization of outside air heat to the underground heat reserve. The heat moving efficiency of the heat pump can be improved by moving heat from high-temperature energy of summer in winter, and moving heat from low-temperature energy of winter in summer.