A refrigerating and air-conditioning apparatus comprising: a main refrigerant circuit in which a compressor, a condenser, a first decompression device, and an evaporator are connected circularly through a refrigerant pipe, wherein the compressor includes an injection pipe; a subcooling refrigerant circuit including a heat exchanger configured to cool a refrigerant on an outflow side of the condenser, a bypass connecting the refrigerant pipe on upstream of the heat exchanger and the refrigerant pipe on downstream of the heat exchanger, wherein the bypass is configured to bypass the heat exchanger and transfer part of the refrigerant condensed at the condenser to the refrigerant pipe on downstream of the heat exchanger, wherein the subcooling refrigerant circuit further includes a second decompression device configured to decompress the refrigerant branching between an exit of the bypass and the first decompression device, wherein the heat exchanger is configured to subcool the refrigerant discharged from the condenser through heat exchange between the refrigerant transferred from the second decompression device and the refrigerant discharged from the condenser, and wherein the subcooling refrigerant circuit is configured to transfer the refrigerant transferred from the second decompression device and subjected to heat exchange at the heat exchanger to the injection pipe of the compressor, characterized in that the second decompression device comprises a variable flow control valve configured to control a flow rate, the bypass includes a variable flow control valve or an openable and closable switching valve configured to adjust a flow rate of the refrigerant, and the refrigerating and air-conditioning apparatus further comprises a refrigerant temperature sensor configured to detect a temperature of the refrigerant in the refrigerant pipe between the condenser and the first decompression device; an outdoor-air temperature sensor configured to detect a temperature of outdoor air; and a flow rate control device configured to control the flow control valve or the switching valve based on the temperature of the refrigerant detected by the refrigerant temperature sensor and the temperature of outdoor air detected by the outdoor-air temperature sensor. a main refrigerant circuit in which a compressor, a condenser, a first decompression device, and an evaporator are connected circularly through a refrigerant pipe, wherein the compressor includes an injection pipe; a subcooling refrigerant circuit including a heat exchanger configured to cool a refrigerant on an outflow side of the condenser, a bypass connecting the refrigerant pipe on upstream of the heat exchanger and the refrigerant pipe on downstream of the heat exchanger, wherein the bypass is configured to bypass the heat exchanger and transfer part of the refrigerant condensed at the condenser to the refrigerant pipe on downstream of the heat exchanger, wherein the subcooling refrigerant circuit further includes a second decompression device configured to decompress the refrigerant branching between an exit of the bypass and the first decompression device, wherein the heat exchanger is configured to subcool the refrigerant discharged from the condenser through heat exchange between the refrigerant transferred from the second decompression device and the refrigerant discharged from the condenser, and wherein the subcooling refrigerant circuit is configured to transfer the refrigerant transferred from the second decompression device and subjected to heat exchange at the heat exchanger to the injection pipe of the compressor, characterized in that the second decompression device comprises a variable flow control valve configured to control a flow rate, the bypass includes a variable flow control valve or an openable and closable switching valve configured to adjust a flow rate of the refrigerant, and the refrigerating and air-conditioning apparatus further comprises a refrigerant temperature sensor configured to detect a temperature of the refrigerant in the refrigerant pipe between the condenser and the first decompression device; an outdoor-air temperature sensor configured to detect a temperature of outdoor air; and a flow rate control device configured to control the flow control valve or the switching valve based on the temperature of the refrigerant detected by the refrigerant temperature sensor and the temperature of outdoor air detected by the outdoor-air temperature sensor.