A refrigeration cycle apparatus comprising: a refrigerant circuit comprising a compressor , a condenser , an expansion valve , an evaporator , and an internal heat exchanger ; a controller ; a condenser fan ; an evaporator fan ; and a refrigerant suitable for flowing in the refrigerant circuit in order of the compressor , the condenser , the internal heat exchanger , the expansion valve , the evaporator , and the internal heat exchanger , the refrigerant being a hydrocarbon refrigerant which is selected from the group consisting of propane, isobutene, pentane, butane, ethane and propylene, the internal heat exchanger comprising: an inner pipe connected to the condenser and the expansion valve ; and an outer pipe connected to the evaporator and the compressor , the inner pipe being inserted in the outer pipe , the internal heat exchanger being configured to cause heat exchange between the refrigerant flowing inside the inner pipe in a direction from the condenser toward the expansion valve , and the refrigerant flowing inside the outer pipe and outside the inner pipe in a direction from the evaporator toward the compressor , wherein the controller is electrically connected to the compressor , the expansion valve , the condenser fan and the evaporator fan and is configured to control operations thereof so that the refrigerant flowing inside the outer pipe and outside the inner pipe is entirely gas. a refrigerant circuit comprising a compressor , a condenser , an expansion valve , an evaporator , and an internal heat exchanger ; a controller ; a condenser fan ; an evaporator fan ; and a refrigerant suitable for flowing in the refrigerant circuit in order of the compressor , the condenser , the internal heat exchanger , the expansion valve , the evaporator , and the internal heat exchanger , the refrigerant being a hydrocarbon refrigerant which is selected from the group consisting of propane, isobutene, pentane, butane, ethane and propylene, the internal heat exchanger comprising: an inner pipe connected to the condenser and the expansion valve ; and an outer pipe connected to the evaporator and the compressor , the inner pipe being inserted in the outer pipe , the internal heat exchanger being configured to cause heat exchange between the refrigerant flowing inside the inner pipe in a direction from the condenser toward the expansion valve , and the refrigerant flowing inside the outer pipe and outside the inner pipe in a direction from the evaporator toward the compressor , wherein the controller is electrically connected to the compressor , the expansion valve , the condenser fan and the evaporator fan and is configured to control operations thereof so that the refrigerant flowing inside the outer pipe and outside the inner pipe is entirely gas. an inner pipe connected to the condenser and the expansion valve ; and an outer pipe connected to the evaporator and the compressor , the inner pipe being inserted in the outer pipe , the internal heat exchanger being configured to cause heat exchange between the refrigerant flowing inside the inner pipe in a direction from the condenser toward the expansion valve , and the refrigerant flowing inside the outer pipe and outside the inner pipe in a direction from the evaporator toward the compressor , wherein the controller is electrically connected to the compressor , the expansion valve , the condenser fan and the evaporator fan and is configured to control operations thereof so that the refrigerant flowing inside the outer pipe and outside the inner pipe is entirely gas. <EOS>