To prevent dielectric breakdown from being generated even if foreign matters are mixed into a semiconductive layer or even if small protrusions are present on the front surface, by providing two or more semiconductive layers having the different volume resistivity between a conductor and an insulator and between the insulator and an outer shield layer.

A semiconductive resin component obtained by mixing conductive carbon black, antioxidant, cross linking agent and cross linking auxiliary agent to base polymer such as ethylene-vinyl acetate copolymer and ethlene- ethyle acrylate copolymer is processed into a tape shape, and semiconductive tapes 2, 4 having the thickness in the range of 0.5 to 2mm and having the different volume resistivity are provided. The inner semiconductive tape 2 comprising three layers 2a, 2b, 2c having the different volume resistivity is wrapped on a conductor 1, and an insulator 3 is provided on it. The semiconductive tape 4 of three layers 3a, 3b, 3c having the different volume resistivity is wound on the insulator 3, and an outer shield layer 5 and a sheath 6 are provided on it.