PURPOSE: To avert direct contacting of tensile wires with an optical fiber unit and to protect the optical fiber unit against side pressure by covering the optical fiber unit with a thick-walled small diameter pipe using a plastic material of high tensile strength.

CONSTITUTION: A tensile wire 1 is provided at the center of a cable, and the circumference thereof is enclosed with a cushion body 3 consisting of a material having small Young's modulus such as silicone rubber or elastomer. Optical fibers 2 are disposed at a constant interval in the body 3 so as not to contact with each other, whereby an optical fiber unit is constituted. The optical fiber unit is stored in a plastic pipe 4 and the outside circumference of the unit is in tight contact with the pipe 4. Tensile wires 5 are aggregated on the outside circumference of the pipe 4 in tight contact therewith. A metallic tube 6 of copper or aluminum is formed on the outer side of the wires 5, and a PE insulator 7 is formed by extrusion molding on the outside circumference of the tube 6. If necessary, an external jacket 8 is provided.