An ice making system includes: a refrigerant circuit that performs a vapor compression refrigeration cycle and that includes a compressor, a condenser that condenses refrigerant discharged from the compressor, a first expansion valve with an adjustable opening degree that decompresses the refrigerant from the condenser, a flooded evaporator that evaporates the refrigerant decompressed by the first expansion valve, and a superheater that imparts a degree of superheating to the refrigerant discharged from the flooded evaporator; a circulation circuit that circulates a medium that is cooled by the flooded evaporator; and a control device that controls the adjustable opening degree of the first expansion valve such that the superheater imparts to the refrigerant discharged from the flooded evaporator a degree of superheating at which dryness of the refrigerant is kept within a predetermined range of less than 1.