Abstract: A core cable is composed of a core member, a conductor spirally wound around the core member, and an insulator covering the outer surface of a layer of the spirally wound conductor. For the core member and insulator, elastic and deformable materials are used, and the core member, conductor, and insulator stretch and contract integrally with each other. When using a non-elastic core member and insulator, a plurality of core cables are spirally wound together to be formed like a coil and then covered with an elastic and deformable sheath so as to be finished into a single line of cable which stretches and contracts due to elasticity of coil-like cables and sheath.