A closed type refrigerator comprising: a motor having a rotation shaft; a compressor coupled to one end of said rotation shaft; an expansion turbine coupled to the other end of said rotation shaft; a refrigerant circulating pipe configured to circulate a refrigerant from an outlet of said compressor and an inlet of said expansion turbine and from an outlet of said expansion turbine to an inlet of said compressor to form a closed loop for a flow route of said refrigerant; a first heat exchanger provided in a portion of said refrigerant circulating pipe from the outlet of said compressor to the inlet of said expansion turbine; a second heat exchanger provided in a portion of said refrigerant circulating pipe from said first heat exchanger to the inlet of said expansion turbine; and wherein said compressor compresses said refrigerant which is dry air or dry nitrogen, said first heat exchanger carries out heat exchange between the compressed refrigerant and atmosphere to generate a first cooled refrigerant, said second heat exchanger carries out heat exchange between the first cooled refrigerant and a second cooled refrigerant to generate a third cooled refrigerant, said expansion turbine adiabatically expands the third cooled refrigerant to generate the second cooled refrigerant, which is used to cool a refrigeration storage and supplied to the inlet of said compressor, and said refrigerant is dehumidified and is hermetically closed in said refrigerant circulating pipe such that said refrigerant does not condense even when said refrigerant is cooled to a minimum temperature in said refrigerant circulating pipe, characterized by a brine heat exchanger provided in a portion of said refrigerant circulating pipe between the outlet of said expansion turbine and said second heat exchanger to carry out heat exchange between said second cooled refrigerant and a brine in a brine line, wherein said brine line forms a closed loop and a portion of said brine line is arranged in said refrigeration storage. a motor having a rotation shaft; a compressor coupled to one end of said rotation shaft; an expansion turbine coupled to the other end of said rotation shaft; a refrigerant circulating pipe configured to circulate a refrigerant from an outlet of said compressor and an inlet of said expansion turbine and from an outlet of said expansion turbine to an inlet of said compressor to form a closed loop for a flow route of said refrigerant; a first heat exchanger provided in a portion of said refrigerant circulating pipe from the outlet of said compressor to the inlet of said expansion turbine; a second heat exchanger provided in a portion of said refrigerant circulating pipe from said first heat exchanger to the inlet of said expansion turbine; and wherein said compressor compresses said refrigerant which is dry air or dry nitrogen, said first heat exchanger carries out heat exchange between the compressed refrigerant and atmosphere to generate a first cooled refrigerant, said second heat exchanger carries out heat exchange between the first cooled refrigerant and a second cooled refrigerant to generate a third cooled refrigerant, said expansion turbine adiabatically expands the third cooled refrigerant to generate the second cooled refrigerant, which is used to cool a refrigeration storage and supplied to the inlet of said compressor, and said refrigerant is dehumidified and is hermetically closed in said refrigerant circulating pipe such that said refrigerant does not condense even when said refrigerant is cooled to a minimum temperature in said refrigerant circulating pipe, characterized by a brine heat exchanger provided in a portion of said refrigerant circulating pipe between the outlet of said expansion turbine and said second heat exchanger to carry out heat exchange between said second cooled refrigerant and a brine in a brine line, wherein said brine line forms a closed loop and a portion of said brine line is arranged in said refrigeration storage.