An air-cooled air-conditioning apparatus including a heat source side heat exchanger comprising a plural number of heat source side heat exchanger parts that are connected together, and each of the heat source side heat exchanger parts is connected by a corresponding flow switching valve to a compressor. The air-cooled air-conditioning apparatus includes a controller configured to perform a defrosting operation in which a refrigerant discharged from the compressor is caused to flow separately through each of the heat source side heat exchanger parts by opening and closing the corresponding flow switching valves. The controller performs the defrosting operation on the basis of the heat exchanger capacity of each of the heat source side heat exchanger parts, the necessary heating capacity of each of the heat source side heat exchanger parts, and the arrangement of the heat source side heat exchanger parts.