To obtain monofilament that has good abrasion resistance and is useful for screen gauze and the like by applying polysiloxane and/or a fluorine resin to monofilaments of high strength and high elasticity.

Monofilaments having a strength of ≥12 g/d and an elasticity of ≥300 g/d (for example, molten, liquid crystalline polyester or p-oriented aramide) is treated with ≥1 wt.% of polysiloxane and/or a fluorine resin. In a preferred embodiment, the polysiloxane is a polymer having the recurring units of the formula [X1-X4 are independently H, OH, COOH, alkyl or the like; m and n are independently an integer of ≥1.