To provide an air conditioning system capable of achieving energy saving.

The air conditioning system includes: thermal storage media 24A, 25A installed in a room 21A on an upper floor 20 which is a second floor or an upper floor; an underground or semi-underground heat storage tank 15; and an air sending system 30. The air sending system 30 is brought into a first state for blowing out air taken in from an air passage 4 on a roof between a roof face 2 and a photovoltaic panel 3 to the inside of the room 21A and a second state for blowing out air taken in from the heat storage tank 15 to the inside of the room 21A.