Provided is an antibacterial cosmetic brush hairs with long-lasting antibacterial properties, wherein the running off of the antibacterial agent after washing, etc. is prevented by treating synthetic fibers with a phenol compound and one or more quaternary ammonium salts selected from among: alkyl ammonium salt, alkyl benzyl ammonium salt, and alkyl pyridinium salt. Further provided is an antibacterial cosmetic applicator that uses the brush hairs.
