A composite cable 21 with a plug 22 attached thereto includes optical fibers, metal wires, a tensile strength fiber 21a, and an envelope 21b for enveloping them and the plug 22 includes a ferrule 210 of the plug for connecting the optical fiber, a cable clamp 221 and a Kevler holder 222 (first fixing mechanism) for fixing the tensile strength fiber 21a, and a gasket 223 (second fixing mechanism) for blocking a twist of the envelope 21b and further includes a joint mechanism (227) of a detachable traction cap for pulling the composite cable 21 and inserting the composite cable 21 into piping.