An air-conditioning apparatus comprising: a compressor configured to compress refrigerant; a flow switching device configured to switch a flow passage of the refrigerant discharged from the compressor between a flow passage used for a cooling operation and a flow passage used for a heating operation; a heat source side heat exchanger serving as a condenser in the cooling operation and as an evaporator in the heating operation; an expansion device configured to expand and decompress the refrigerant; and a use side heat exchanger serving as an evaporator in the cooling operation and as a condenser in the heating operation, characterized by an internal heat exchanger including a first flow passage guiding the refrigerant flowing between the evaporator and the compressor, a second flow passage guiding the refrigerant flowing between the heat source side heat exchanger and the expansion device, and a third flow passage guiding the refrigerant flowing between the expansion device and the use side heat exchanger, the internal heat exchanger being configured to exchange heat between the refrigerant flowing through the first flow passage and the refrigerant flowing through the second flow passage in the cooling operation, and exchange heat between the refrigerant flowing through the first flow passage and the refrigerant flowing through the third flow passage in the heating operation, the internal heat exchanger including a first heat transfer pipe in which the first flow passage is formed, a second heat transfer pipe in which the second flow passage is formed, and a third heat transfer pipe in which the third flow passage is formed, the internal heat exchanger being configured to exchange heat between the refrigerant flowing through the second heat transfer pipe and the refrigerant flowing through the first heat transfer pipe and exchange heat between the refrigerant flowing through the third heat transfer pipe and the refrigerant flowing through the first heat transfer pipe. a compressor configured to compress refrigerant; a flow switching device configured to switch a flow passage of the refrigerant discharged from the compressor between a flow passage used for a cooling operation and a flow passage used for a heating operation; a heat source side heat exchanger serving as a condenser in the cooling operation and as an evaporator in the heating operation; an expansion device configured to expand and decompress the refrigerant; and a use side heat exchanger serving as an evaporator in the cooling operation and as a condenser in the heating operation, characterized by an internal heat exchanger including a first flow passage guiding the refrigerant flowing between the evaporator and the compressor, a second flow passage guiding the refrigerant flowing between the heat source side heat exchanger and the expansion device, and a third flow passage guiding the refrigerant flowing between the expansion device and the use side heat exchanger, the internal heat exchanger being configured to exchange heat between the refrigerant flowing through the first flow passage and the refrigerant flowing through the second flow passage in the cooling operation, and exchange heat between the refrigerant flowing through the first flow passage and the refrigerant flowing through the third flow passage in the heating operation, the internal heat exchanger including a first heat transfer pipe in which the first flow passage is formed, a second heat transfer pipe in which the second flow passage is formed, and a third heat transfer pipe in which the third flow passage is formed, the internal heat exchanger being configured to exchange heat between the refrigerant flowing through the second heat transfer pipe and the refrigerant flowing through the first heat transfer pipe and exchange heat between the refrigerant flowing through the third heat transfer pipe and the refrigerant flowing through the first heat transfer pipe.