PURPOSE: To reduce the residual strain for production by inserting an optical cable through a wheel type capstan to control the excess length of the optical fiber.

CONSTITUTION: Plural optical fibers 1 are supplied an are roughly stranded to form an optical fiber unit 3, and this unit 3 is inserted to a cylindrically formed LAP tape 4 and is coated with high-tensile wires 5 and a sheath to obtain an optical cable 8, and this optical cable 8 is wound up around a take-up drum 10 through a capstan 9. Differences of storage position of tension resisting wires 5 and Young's modulus of optical cable constituting materials are used to make the center of bend of the optical cable 8 and that of the optical fiber unit 3 different from each other, and the difference of layer diameter between the center of bend of the optical cable 8 and that of optical fibers 1 or the optical fiber unit 3 is used to give an excess length to stored optical fibers. The condition of a formula is satisfied where D1 is the wheel diameter of the wheel type capstan 11 and D2 is the diameter of the take-up drum 10 and D is the diameter of the optical cable 8, thereby reducing the elongation strain remaining in optical fibers 1 at the time of production.