To improve winding and slipping off in a carding process and enable formation of spun yarn by attaching a specific hydrophilic fluorine-based surfactant to a polyfluorocarbon staple fiber.

One or two or more anionic hydrophilic fluorine-based surfactants selected from a group comprising a perfluoroalkylsulfonic acid salt and a perfluoroalkyl-(sulfonamidealkyl)phosphate, having a 4-8C perfluoroalkyl group, preferably having a branched perfluoropropene oligomer comprising hexafluoropropene oligomer having 2-4 average recurring numbers as a perfluoroalkyl group and having an alkali metal salt, an organic ammonium salt or organic phosphonium salt as a sulfonic acid salt are attached in an amount of 0.1-2.0 wt.% to a polyfluorocarbon staple fiber having 30-120 mm average fiber length and 1.1×10-4 to 2.2×10-3 g/m fineness and the fiber is spun.