A wholly aromatic polyamide fiber containing above about 600 ppm (about 0.2 mole percent) of sulfonate in the polymer main chain is provided. The sulfonate is represented by the general formulas (III) or (IV): ##STR1## where M is hydrogen, a metal cation, or a quaternary ammonium ion. The fiber exhibits excellent dyeability and can be cation-dyed without the use of a dye carrier.