It is to provide a disinfectant liquid which enables easy identification of the application sites in preoperative skin disinfection and the like, where the liquid is obtained by coloring an aqueous solution of olanexidine gluconate which is a colorless and transparent liquid. A disinfectant liquid comprises olanexidine gluconate, a coloring agent such as Sunset Yellow FCF, an alkyl dimethylamine oxide such as lauryl dimethylamine oxide, and optionally one or more surfactants other than alkyl dimethylamine oxide such as polyoxyethylene alkyl ether including lauromacrogol and polyoxyethylene polyoxypropylene alkyl ether including polyoxyethylene(20) polyoxypropylene(4) cetyl ether. The disinfectant liquid enables easy identification of the application sites in preoperative skin disinfection and the like.