PROBLEM TO BE SOLVED: To provide a method for producing a spun yarn capable of easily removing polymeric contaminating string- or film-shaped materials contaminated in the raw material of a natural fiber such as cotton, silk or the like in its spinning process. SOLUTION: This method for producing the spun yarn by using the natural fiber such as cotton, silk or the like containing the string- or film-shaped polymeric contaminating materials, as the raw material is provided by performing a heat treatment on the natural fiber containing the polymeric contaminant at or higher temperature than the softening point of the polymeric contaminant and lower than the thermal decomposition point of the natural fiber to make the string- or film-shaped polymeric contaminants as lumpy materials in any of the production processes of the spun yarn and then removing the lumpy materials in the production processes of the spun yarn. COPYRIGHT: (C)2004,JPO
