To provide a connecting section of a power DC coaxial cable which has a small outside diameter increase in a connecting section, can be manufactured readily and has little defects.

Two heat-shrinkage insulating tubes 11 with internal semiconductive layers are installed in series on the external side of exposure sections S of return conductors 5 so as to make them subjected to heat-shrinking. Internal semiconductive layers 12 and 12 of the tubes are connected and insulating layers 13 and 13 of the tubes are connected, in a part where the ends of the heat-shrinkable tubes 11 are confronted. The internal semiconductive layers 12 of the tubes and return internal semiconductive layers 6 of both cables are connected, and the insulating layers 13 of the tubes and return insulating layers 7 of both cables are connected, at a part where the ends of the heat-shrunk tubes 11 are confronted with the ends of the return internal semiconductive layers 6 and the return insulating layers 7 of the cables.