The present invention provides a fiber containing syndiotactic polystyrene that exhibits dyeability with disperse dyes and shrinkage at high temperatures equivalent to those of polyester fibers. [Solution] The fiber is characterized by containing a mixture of syndiotactic polystyrene A and atactic polystyrene B, wherein the amount of atactic polystyrene B is 15 to 50 parts by mass per 100 parts by mass of the total of syndiotactic polystyrene A and atactic polystyrene B, wherein the crystallite size D(110) in the (110) plane determined by X-raydiffraction is greater than 0 Å and 75 Å or less, and the crystallite size D(002) in the (002) plane is 75 Å or more and 110 Å or less.