An air conditioning system includes: an intake unit configured to take in return air of an indoor space from a ceiling of the indoor space; an outdoor air processing unit configured to supply outdoor air while exhausting the return air taken in via the intake unit to outdoors; an air conditioner configured to supply, as air-conditioning air, mixed air of the return air taken in via the intake unit and the outdoor air supplied by the outdoor air processing unit; and at least one radiation unit disposed in the indoor space in a manner to surround the intake unit, the radiation unit being configured to radiate heat of the air-conditioning air supplied by the air conditioner while discharging the air-conditioning air to the indoor space.