An air-conditioning apparatus, comprising: a refrigeration cycle for circulating refrigerant therethrough, in which a compressor, a first heat exchanger, a first passage of a subcooling heat exchanger for exchanging heat between high-temperature refrigerant and low-temperature refrigerant to subcool the high-temperature refrigerant, a first expansion device, a second heat exchanger, and an accumulator are connected to each other by refrigerant pipes, the compressor including an injection port for introducing the refrigerant from outside into a compression chamber of the compressor, the accumulator being arranged on a suction side of the compressor; a first bypass pipe branched from one of the refrigerant pipes between the first heat exchanger and the second heat exchanger and connected to an inlet-side passage of the accumulator through a second expansion device, a second passage of the subcooling heat exchanger for exchanging heat between the refrigerant flowing through the second passage of the subcooling heat exchanger and the refrigerant flowing through the first passage of the subcooling heat exchanger, and a first opening and closing device; a second bypass pipe branched from the first bypass pipe between the subcooling heat exchanger and the first opening and closing device and connected to the injection port of the compressor through a second opening and closing device; characterised by further comprising: a third bypass pipe branched from the one of the refrigerant pipes between the first heat exchanger and the second heat exchanger and connected to an other of the refrigerant pipes between an inlet side of the compressor and an outlet side of the accumulator through a third expansion device; and a liquid separator configured to extract a part of liquid refrigerant from the refrigerant flowing between the first heat exchanger and the second heat exchanger, wherein the liquid separator includes a pipe connected to an extraction port for the liquid refrigerant, the pipe being branched and connected to the second expansion device and the third expansion device. a refrigeration cycle for circulating refrigerant therethrough, in which a compressor, a first heat exchanger, a first passage of a subcooling heat exchanger for exchanging heat between high-temperature refrigerant and low-temperature refrigerant to subcool the high-temperature refrigerant, a first expansion device, a second heat exchanger, and an accumulator are connected to each other by refrigerant pipes, the compressor including an injection port for introducing the refrigerant from outside into a compression chamber of the compressor, the accumulator being arranged on a suction side of the compressor; a first bypass pipe branched from one of the refrigerant pipes between the first heat exchanger and the second heat exchanger and connected to an inlet-side passage of the accumulator through a second expansion device, a second passage of the subcooling heat exchanger for exchanging heat between the refrigerant flowing through the second passage of the subcooling heat exchanger and the refrigerant flowing through the first passage of the subcooling heat exchanger, and a first opening and closing device; a second bypass pipe branched from the first bypass pipe between the subcooling heat exchanger and the first opening and closing device and connected to the injection port of the compressor through a second opening and closing device; a third bypass pipe branched from the one of the refrigerant pipes between the first heat exchanger and the second heat exchanger and connected to an other of the refrigerant pipes between an inlet side of the compressor and an outlet side of the accumulator through a third expansion device; and a liquid separator configured to extract a part of liquid refrigerant from the refrigerant flowing between the first heat exchanger and the second heat exchanger, wherein the liquid separator includes a pipe connected to an extraction port for the liquid refrigerant, the pipe being branched and connected to the second expansion device and the third expansion device.