Provided is a carbon fiber that has an average fiber diameter of 1-100 m and is a product obtained by spinning a solution of chlorinated polyvinyl chloride to obtain a chlorinated polyvinyl fiber, elongating the chlorinated polyvinyl fiber without an oxidative stabilization process, and then preheating and carbonizing the elongated polyvinyl chloride fiber. Also, provided is a method for preparing a carbon fiber which has excellent mechanical properties and a high degree of orientation without oxidative stabilization.

An acrylonitrile-containing fiber includes 100 parts by mass of a polymer including at least 15 parts by mass of acrylonitrile; and 1.0 to 50 parts by mass of a water absorbent resin having a pure water absorption capacity (g/g) with respect to its own weight of at least 10 but less than 100, wherein the fiber is dyeable with a disperse dye.

An acrylonitrile-containing fiber includes 100 parts by mass of a polymer including at least 15 parts by mass of acrylonitrile; and 1.0 to 50 parts by mass of a water absorbent resin having a pure water absorption capacity (g/g) with respect to its own weight of at least 10 but less than 100, wherein the fiber is dyeable with a disperse dye.

An acrylonitrile-containing fiber includes 100 parts by mass of a polymer including at least 15 parts by mass of acrylonitrile; and 1.0 to 50 parts by mass of a water absorbent resin having a pure water absorption capacity (gig) with respect to its own weight of at least 10 but less than 100, wherein the fiber is dyeable with a disperse dye.

An acrylonitrile-containing fiber includes 100 parts by mass of a polymer including at least 15 parts by mass of acrylonitrile; and 1.0 to 50 parts by mass of a water absorbent resin having a pure water absorption capacity (gig) with respect to its own weight of at least 10 but less than 100, wherein the fiber is dyeable with a disperse dye.