PURPOSE: To obtain the title fiber having fiber characteristics of a synthetic resin as well as characteristics which additive has by mixing powder having characteristics different from that of the synthetic resin into melted synthetic resin and then jetting the mixture from a nozzle.

CONSTITUTION: Powder (e.g. 'Sandalon(R) powder') having characteristics different from that of a synthetic resin is mixed into melted synthetic resin (e.g. nylon resin) and the melted synthetic resin in which the powder is mixed is jetted from a nozzle to provide the aimed fiber. Furthermore, the above mentioned powder includes preferably powder having characteristics capable of generating far-infrared ray, natural fiber powder or ceramic powder.