To provide a rayon fiber has a functionalizing agent applied during a viscose rayon production process without deactivation and/or decline in its function, thus having functionality imparted thereby, and excellent in thus imparted functionality's persistence, and to provide a method for producing the rayon fiber.

The rayon fiber is such that a fatty acid and/or a salt thereof (hereinafter, referred to as fatty acid simply) and a functionalizing agent (except liposoluble antioxidant and tea-derived ingredients) are applied therein; the cellulose therein and the fatty acid are incompatible with each other; the fatty acid has been microdispersed therein to form cell-like regions; the functionalizing agent is included in the cell-like regions. The method for producing the rayon fiber includes the following steps: an aqueous solution containing the fatty acid is admixed with the functionalizing agent to prepare a mixed solution; Cellulose-containing viscose dope is admixed with the above-obtained mixed solution to prepare viscose dope, which is then extruded via nozzles and spun followed by coagulating and regenerating the resultant spun rayon fiber.