To provide an air conditioning system capable of enhancing efficiency of air conditioning and capable of enhancing energy saving properties.

An air conditioning system has switching means V1, V2, V3, V4 for switching a first water feeding channels 151, 152, 153, 154 for heating in winter seasons for feeding underground water or other from a first temperature zone W1 to a second temperature zone W2 via a heat pump section 111, a heat absorbing and radiating section 112 and second water feeding channels 154, 157, 114, 156, 151 for cooling in summer seasons for feeding the underground water or others from the second temperature zone W2 to the first temperature zone W1 via the heat absorbing and radiating section 112, and a temperature difference generating means for bringing a temperature difference of the underground water or other at an entrance and an exit of the heat pump section 111 into a temperature of ≥8°C.