To provide a heating and cooling system capable of effectively using an underfloor space and operable inexpensively.

The heating and cooling system includes a heat pump 6 as a heating source, an indoor unit 4 through which heat carrying fluid from the heat pump 6 is made to flow to perform heat exchange with air inside a room 15 of a unit building U, and a heat storage part 2 which is arranged in the underfloor space 14 of the unit building U and through which the heat carrying fluid from the heat pump 6 is made to flow. A heat exchanger route 5 for circulating a refrigerant in the indoor unit 4 and a heat storage route 3 for circulating hot water or cold water to the heat storage part 2 are connected to the heat pump 6, respectively.