An air conditioner is provided that includes an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, heats the heat transfer medium, an absorption chiller driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, an indoor unit to which the refrigerant is supplied through the refrigerant passage, a heat transfer medium temperature detector for detecting the temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detector for detecting the temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device.