An air conditioning system for controlling air conditioning in a room in accordance with an air conditioning operation instruction received from a user includes: a ventilation device ventilating the room; an air agitation device agitating air in the room; an air conditioner controlling the air conditioning of the room and operations of the ventilation device and the air agitation device; and a detection device detecting presence of the user in the room. The air conditioner controls the operations of the ventilation device and the air agitation device before the user enters the room based on an indoor temperature inside the room, an outdoor temperature outside the room, an operation mode of air conditioning control performed by the air conditioner included in the air conditioning operation instruction, an operating status of the ventilation device, and a detection result provided by the detection device.