To greatly reduce a heat loss by arranging a polished outer surface constructed of a reflective material layer in a spacer member in a low temperature fluid transfer line provided with the spacer member between an internal tube and an outer tubular envelope.

Along a low temperature transfer pipe 2 serving as a main component for a simple low temperature fluid transfer line, spacer members 3 are arranged at fixed intervals with their angles to the pipe axis shifted from each other, and an envelope 1 is supported concentrically with the pipe 2 by means of the spacer members 3. The low temperature transfer pipe 2 is surrounded by a super heat-insulator sleeve 4 made by winding, for example. The spacer member 3 is made of low thermal conductivity non-metal material such as glass fiber impregnated with epoxy resin, and the outer surface of the spacer member 3 is processed by covering with a metallic coating, preferably, by plating/depositing aluminum. In this way, a heat loss in the low temperature transfer pipe 2 can be reduced greatly.