The invention provides a coaxial cable possessing internal conductor, internal insulation layer covered with the conductor, external conductor disposed outside of the internal insulation layer and external insulation layer covered with the external conductor. In the coaxial cable, internal insulation layer, external insulation layer or two of these are made of ionomer resin composition containing ethene series ionomer resin and organic clay. In addition, the present invention provides not only method for manufacturing the coaxial cable, but multi-core coaxial cable containing the coaxial cable. The coaxial cable is compatible in mechanical property and reduction of wall thickness of insulation layer and the diameter is reduced, in addition the coaxial cable has excellent flexible property.