A refrigerating apparatus comprising a refrigerant circuit including a low pressure side compressor, a high pressure side compressor, and an intermediate-pressure refrigerant gas-liquid separator for performing two-stage compression/two-stage expansion refrigeration cycle, wherein the refrigerant circuit is switchable from/to a heating cycle to/from a defrosting cycle by circulating refrigerant reversibly in the refrigerant circuit, in the heating cycle, the refrigerant being subjected to the two-stage compression/two-stage expansion in which refrigerant discharged from the low pressure side compressor is compressed in the high pressure side compressor while condensed refrigerant flows into the gas-liquid separator and gas refrigerant in the gas-liquid separator is sucked into the high pressure side compressor, and characterised in that the defrosting cycle comprises a first defrosting operation in which the refrigerating apparatus is configured such that the high pressure side compressor is stopped and only the low pressure side compressor is operated, the refrigerant being subjected to single-stage compression/single stage expansion in the first defrosting operation in which refrigerant discharged from the low pressure side compressor and then condensed bypasses the gas-liquid separator and thereafter evaporates, the evaporated refrigerant bypassing the high pressure side compressor, a second defrosting operation in which the refrigerating apparatus is configured such that both of the low pressure side compressor and the high pressure side compressor are operated, and wherein the refrigeration apparatus is configured such that gas refrigerant in the gas-liquid separator is sucked into the high pressure side compressor and the refrigerant discharged from the high pressure side compressor merges with the evaporated refrigerant, and is then sucked into the low pressure side compressor, and the refrigerant circuit includes an injection pipe for injecting part of refrigerant discharged from the high pressure side compressor into a suction side of the high pressure side compressor, the refrigerating apparatus is configured such that the refrigerant injected by the injection pipe merges with refrigerant from the gas-liquid separator in the second defrosting operation. wherein the refrigerant circuit is switchable from/to a heating cycle to/from a defrosting cycle by circulating refrigerant reversibly in the refrigerant circuit, in the heating cycle, the refrigerant being subjected to the two-stage compression/two-stage expansion in which refrigerant discharged from the low pressure side compressor is compressed in the high pressure side compressor while condensed refrigerant flows into the gas-liquid separator and gas refrigerant in the gas-liquid separator is sucked into the high pressure side compressor, and characterised in that the defrosting cycle comprises a first defrosting operation in which the refrigerating apparatus is configured such that the high pressure side compressor is stopped and only the low pressure side compressor is operated, the refrigerant being subjected to single-stage compression/single stage expansion in the first defrosting operation in which refrigerant discharged from the low pressure side compressor and then condensed bypasses the gas-liquid separator and thereafter evaporates, the evaporated refrigerant bypassing the high pressure side compressor, a second defrosting operation in which the refrigerating apparatus is configured such that both of the low pressure side compressor and the high pressure side compressor are operated, and wherein the refrigeration apparatus is configured such that gas refrigerant in the gas-liquid separator is sucked into the high pressure side compressor and the refrigerant discharged from the high pressure side compressor merges with the evaporated refrigerant, and is then sucked into the low pressure side compressor, and the refrigerant circuit includes an injection pipe for injecting part of refrigerant discharged from the high pressure side compressor into a suction side of the high pressure side compressor, the refrigerating apparatus is configured such that the refrigerant injected by the injection pipe merges with refrigerant from the gas-liquid separator in the second defrosting operation.