System for supplying liquefied natural gas fuel

Disclosed is an LNG fuel supply system, including: a fuel supply line (21) connected from an LNG storing tank (10) to an engine (20); a pump (32) provided on the fuel supply line, and configured to change an LNG to the LNG in a supercooled liquid state by compressing the LNG discharged from the LNG storing tank at a high pressure; and a heat exchanger (40) provided on the fuel supply line between the engine and the pump, and configured to phase change the LNG in the supercooled liquid state to the LNG in a supercritical state by heating the LNG in the supercooled liquid state supplied from the pump.