An air conditioning control system allows a supply air switching controller to alternately switch outside air control and return air control at a preset switching interval. The supply air switching controller is connected to an air conditioner placed to correspond to each room inside as an air conditioning control subject. The outside air control takes outside air into a temperature/humidity adjustment coil of the air conditioner by opening a first damper provided in the air conditioner in order to adjust an intake volume of the outside air into the air conditioner and by closing a second damper provided in the air conditioner in order to adjust an intake volume of return air from the room inside. The return air control takes the return air from the room inside into the temperature/humidity adjustment coil of the air conditioner by closing the first damper and opening the second damper.