An air conditioner includes: use-side units that are each switchable between a cooling operation and a heating operation; and a heat-source-side unit including a compressor, a discharge pipe through which a refrigerant discharged from the compressor flows, a first main heat-source-side flow path and a second main heat-source-side flow path that branch off from the discharge pipe, a first heat-source-side heat exchanger, a second heat-source-side heat exchanger, a first economizer heat exchanger, and a second economizer heat exchanger. The first heat-source-side heat exchanger is connected to the first economizer heat exchanger in series in the first main heat-source-side flow path. The second heat-source-side heat exchanger is connected to the second economizer heat exchanger in series in the second main heat-source-side flow path.