Abstract: The present invention relates to a storage tank having a heat exchanger and a natural gas fuel supply system having the storage tank. The storage tank having a heat exchanger according to one aspect of the present invention includes: a heat exchanger installed in an upper portion of an inside space of the storage tank, wherein the heat exchanger includes: an expansion valve into which LNG, which is highly pressurized by a pressurizer, is introduced; and a heat exchanger pipe which guides a flow of the LNG so that the LNG expands in the heat exchanger.