An air conditioner comprising: an outdoor unit ; an indoor unit ; an outdoor heat exchanger disposed in the outdoor unit ; an indoor heat exchanger disposed in the indoor unit ; a four-way valve disposed in the outdoor unit , and configured to switch a flow path and allow refrigerant to be transferred to any one of the outdoor heat exchanger and the indoor heat exchanger ; a compressor configured to compress the refrigerant; a refrigerant pipe configured to connect the outdoor heat exchanger and the indoor heat exchanger ; a refrigerant ratio adjusting device provided at the refrigerant pipe and configured to adjust a ratio between a liquid refrigerant and a gaseous refrigerant passing through the refrigerant pipe ; and a controller configured to control the operation of the refrigerant ratio adjusting device , wherein the refrigerant ratio adjusting device includes a plurality of refrigerant ratio adjusting devices sequentially disposed in the refrigerant pipe , and the controller is configured to control the refrigerant ratio adjusting device to decompress stepwise refrigerant flowing from the outdoor heat exchanger to the indoor heat exchanger or from the indoor heat exchanger to the outdoor heat exchanger , characterised in that the controller is configured to adjust a refrigerant decompression amount of one refrigerant ratio adjusting device among the plurality of refrigerant ratio adjusting devices located upstream in a direction that the refrigerant flows, in accordance with a condensation pressure in the outdoor heat exchanger and the indoor heat exchanger where condensation of the refrigerant occurs, such that the controller is configured to decrease the opening degree of the one refrigerant ratio adjusting device when a condensation pressure is lower than a target condensation pressure and increase the opening degree of the one refrigerant ratio adjusting device when a condensation pressure is higher than a target condensation pressure. an outdoor unit ; an indoor unit ; an outdoor heat exchanger disposed in the outdoor unit ; an indoor heat exchanger disposed in the indoor unit ; a four-way valve disposed in the outdoor unit , and configured to switch a flow path and allow refrigerant to be transferred to any one of the outdoor heat exchanger and the indoor heat exchanger ; a compressor configured to compress the refrigerant; a refrigerant pipe configured to connect the outdoor heat exchanger and the indoor heat exchanger ; a refrigerant ratio adjusting device provided at the refrigerant pipe and configured to adjust a ratio between a liquid refrigerant and a gaseous refrigerant passing through the refrigerant pipe ; and a controller configured to control the operation of the refrigerant ratio adjusting device , wherein the refrigerant ratio adjusting device includes a plurality of refrigerant ratio adjusting devices sequentially disposed in the refrigerant pipe , and the controller is configured to control the refrigerant ratio adjusting device to decompress stepwise refrigerant flowing from the outdoor heat exchanger to the indoor heat exchanger or from the indoor heat exchanger to the outdoor heat exchanger , characterised in that the controller is configured to adjust a refrigerant decompression amount of one refrigerant ratio adjusting device among the plurality of refrigerant ratio adjusting devices located upstream in a direction that the refrigerant flows, in accordance with a condensation pressure in the outdoor heat exchanger and the indoor heat exchanger where condensation of the refrigerant occurs, such that the controller is configured to decrease the opening degree of the one refrigerant ratio adjusting device when a condensation pressure is lower than a target condensation pressure and increase the opening degree of the one refrigerant ratio adjusting device when a condensation pressure is higher than a target condensation pressure. <EOS>