A heat pump comprising: a first cycle device (2, 2') connected such that, in a heating operation, a first refrigerant is circulated in an order of a first compressor, a 4-way valve, a first heat exchanger (30, 30'), a second heat exchanger (40, 40'), a first expansion mechanism, a third heat exchanger, the 4-way valve, and the first compressor, and such that, in a cooling operation, the first refrigerant is circulated in an order of the first compressor, the 4-way valve, the third heat exchanger, the first expansion mechanism, the second heat exchanger (40, 40'), the first heat exchanger (30, 30'), the 4-way valve, and the first compressor; and a second cycle device connected such that a second refrigerant is circulated in an order of a second compressor, a fourth heat exchanger, a second expansion mechanism, one of the first heat exchange (30, 30') and the second heat exchanger (40, 40'), and the second compressor, wherein the one of the first heat exchange (30, 30') and the second heat exchanger (40, 40') is a first refrigerant-second refrigerant heat exchanger (40, 30') having a first refrigerant flow path (41, 31') through which the first refrigerant passes and a second refrigerant flow path (42, 32') through which the second refrigerant is heat-exchanged with the first refrigerant while passing, and wherein the fourth heat exchanger and the third heat exchanger are disposed to be at least partially opposite to each other, characterised in that the heat pump further comprises an outdoor fan configured to blow outdoor air to sequentially pass through the fourth heat exchanger and the third heat exchanger wherein the outdoor fan, the first compressor, the fourth heat exchanger, and the third heat exchanger are disposed in an outdoor unit, wherein the outdoor unit further comprises an outdoor-air suction body provided with outdoor-air inlets through which the outdoor air is sucked into the inside of the outdoor unit, and wherein the fourth heat exchanger is at least partially disposed between the out-door inlets and the third heat exchanger. a first cycle device (2, 2') connected such that, in a heating operation, a first refrigerant is circulated in an order of a first compressor, a 4-way valve, a first heat exchanger (30, 30'), a second heat exchanger (40, 40'), a first expansion mechanism, a third heat exchanger, the 4-way valve, and the first compressor, and such that, in a cooling operation, the first refrigerant is circulated in an order of the first compressor, the 4-way valve, the third heat exchanger, the first expansion mechanism, the second heat exchanger (40, 40'), the first heat exchanger (30, 30'), the 4-way valve, and the first compressor; and a second cycle device connected such that a second refrigerant is circulated in an order of a second compressor, a fourth heat exchanger, a second expansion mechanism, one of the first heat exchange (30, 30') and the second heat exchanger (40, 40'), and the second compressor, wherein the one of the first heat exchange (30, 30') and the second heat exchanger (40, 40') is a first refrigerant-second refrigerant heat exchanger (40, 30') having a first refrigerant flow path (41, 31') through which the first refrigerant passes and a second refrigerant flow path (42, 32') through which the second refrigerant is heat-exchanged with the first refrigerant while passing, and wherein the fourth heat exchanger and the third heat exchanger are disposed to be at least partially opposite to each other, characterised in that the heat pump further comprises an outdoor fan configured to blow outdoor air to sequentially pass through the fourth heat exchanger and the third heat exchanger wherein the outdoor fan, the first compressor, the fourth heat exchanger, and the third heat exchanger are disposed in an outdoor unit, wherein the outdoor unit further comprises an outdoor-air suction body provided with outdoor-air inlets through which the outdoor air is sucked into the inside of the outdoor unit, and wherein the fourth heat exchanger is at least partially disposed between the out-door inlets and the third heat exchanger.