1. An air conditioner comprising:
a refrigerant circuit comprising a compressor, a condenser, a pressure-regulating valve, and an evaporator; and
refrigerant flowing through the refrigerant circuit in an order of the compressor, the condenser, the pressure-regulating valve, and the evaporator, wherein the refrigerant is R32, the pressure-regulating valve comprises
a flow path causing the refrigerant flowing from the condenser to flow to the evaporator,
a pressure reference chamber partitioned from the flow path and filled with inert gas, and
a valve portion disposed in the flow path, the pressure-regulating valve is configured to adjust a degree of opening of the valve portion to adjust a flow rate of the refrigerant flowing through the flow path, and the valve portion is configured to
increase the degree of opening when a pressure in the flow path is higher than a pressure in the pressure reference chamber, and
reduce the degree of opening when the pressure in the flow path is lower than the pressure in the pressure reference chamber.
2. The air conditioner according to claim 1, wherein an amount of the
refrigerant flowing through the refrigerant circuit is 300 g or more and 500 g or less.
3. The air conditioner according to claim 1 or 2, wherein
the pressure-regulating valve comprises a capillary, and
the capillary is disposed between the valve portion and the evaporator in the refrigerant circuit.

4. The air conditioner according to claim 1 or 2, wherein
the pressure-regulating valve comprises a capillary, and
the capillary is disposed in parallel with the valve portion in the refrigerant circuit.
5. The air conditioner according to any one of claims 1 to 4, wherein the
compressor is configured to variably control a number of rotations.