A heat pump includes a first cycle device and a second cycle device. The first cycle device is 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, a second heat exchanger, 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, the first heat exchanger, the 4-way valve, and the first compressor. The second cycle device is connected such that a second refrigerant is circulated in an order of a second compressor, a fourth heat exchanger, a second expansion mechanism, the second heat exchanger, and the second compressor.