PURPOSE: To smooth the operational situation of a required compressor and miniaturize equipment in sending out liquefied natural gas with high pressure. CONSTITUTION: In cooling and refrigerating equipment for obtaining liquefied natural gas stored in a tank and reduced in pressure by a pressure reducing valve 19, a coldness and heat accumulating agent in a coldness and heat accumulating means is always cooled by an overcooling heat exchanger 10 and heat exchangers 23, 27 for the coldness and heat accumulating agent. To liquefy the gasified liquefied natural gas, the gas is cooled by the latent heat and sensible heat of the coldness and heat accumulating agent and further cooled by the overcooling heat exchanger 10 to be liquefied and stored in a tank. When the demand for town gas is great, the liquefied natural gas is boosted by a pump and heated by the coldness and heat accumulating agent so that the gas is sent out with high pressure. Thus, the gas can be sent out in the great demand with pressure higher than that received for liquefacation in the small demand of the town gas.