The invention provides a method for connection of counter conductor in supply coaxial DC cable. A power supply DC coaxial cable has a main conductor at the center, a main insulating layer outside the main conductor, and a return conductor comprising a large number of return conductor wires coaxially twisted outside the main insulating layer. In a method for connecting the return conductors at theconnection portion between the power supply DC coaxial cables, a plurality of return conductor wires of the DC coaxial cables on both sides are adjacently arranged to form each return conductor wire bundle, and the ends of the return conductor wire bundles on both sides are faced to each other and then welded together. This enables the time required for welding the return conductor wires to be reduced and provides a method for connecting the return conductors of DC coaxial cables, which is also applicable to the return conductor connection between DC coaxial cables each having a different number of return conductor wires.