Freezer and air conditioner

It has been usual for a freezer having refrigerant cooling means for cooling a refrigerant at the entrance of a flow rate control valve that a performance coefficient lowers when the amount of cooling provided by the refrigerant cooling means is too less and too much. A freezer of the invention has a compressor (2) for compressing a refrigerant, a radiator (3) for radiating heat of the refrigerant, refrigerant cooling means (15) for cooling the refrigerant, a flow rate control valve (4) for regulating the flow rate of the refrigerant, an evaporator (5) for evaporating the refrigerant, and heat exchange amount control means (16) for controlling the amount of heat exchange in the refrigerant cooling means (15). The refrigerant is circulated through the compressor (2), the radiator (3), the refrigerant cooling means (15), the flow rate control valve (4), and the evaporator (5), in that order.