Abstract: A liquefied gas treatment system according to an embodiment of the present invention includes a boil-off gas heat exchanger exchanging heat between boil-off gas, pressurized by a boil-off gas compressor and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit, and the boil-off gas supplied from a liquefied gas storage tank, wherein the boil-off gas heat exchanger cools the boil-off gas, recovered along the boil-off gas supply line, with the boil-off gas, supplied from the liquefied gas storage tank, or flash gas, supplied through a vapor recovery line.