A method for manufacturing an antimicrobial composition includes: providing an aqueous solution containing an active ingredient salt and a reductant； immersing a carbonaceous material in the aqueous solution； thermally drying the aqueous solution at 80-120° C. so as to attach the active ingredient salt to the carbonaceous material； and pyrolyzing the active ingredient salt at 600-800° C. to convert into a particle of the active ingredient attached to the carbonaceous material so as to form the antimicrobial composition.
