To prevent air temperature from rising due to exhaust heat of an air conditioner by effectively using underground temperature.

The cold-hot water air conditioning system is equipped with a cold water tank 13 and a hot water tank 14 disposed under the ground, a heat pump 16, an air conditioning cold water passage 70 formed by an endoergic side of the heat pump 16 and piping returning to the endoergic side of the heat pump 16 via the air conditioner 36, a pump 48 pumping up cold water housed in the cold water tank 13 and circulating cold water of the air conditioning cold water passage 70, an exhaust heat hot water passage 74 pumping up hot water housed in the hot water tank 14 and formed by piping returning to the hot water tank 14 via an exoergic side of the heat pump 16, and a pump 58 circulating the hot water in a summer season. In the heat pump 16, by intermittent operation of starting operation when the cold water of the air conditioning cold water passage 70 becomes a certain temperature or more and stopping operation when the cold water becomes lower than the certain temperature, a temperature of the cold water of the air conditioning cold water passage 70 is raised and lowered within an allowable temperature range.