Use of this precursor fiber facilitates the production of a high-strength, high-modulus carbon fiber.

The invention additionally relates to a method for producing such a carbon fiber, to the use thereof, and to a carbon precursor fiber.

Disclosed is a method for producing a precursor fiber which enables production of a carbon fiber having high strength and high elastic modulus.

The precursor fiber is particularly characterized by having a breaking twist angle of from 17 to 23 degrees.

A precursor fiber is obtained from alumina-silica-based fiber forming concentrate solution for inorganic salt method as a material.

The nanofiber is formed by electrospinning a precursor solution to form a precursor nanofiber.

Provided are carbon fibers which have a thicker single fiber fineness of the polyacrylonitrile-based precursor fiber bundles and lower production costs, and which have excellent mechanical properties.