A method for screening an antimicrobial agent which is capable of controlling microorganisms causing offensive odor in an air-conditioning system and a method for removing offensive odor in an air-conditioning system are provided. The method for screening an antimicrobial agent and the method for removing offensive odor in an air-conditioning system may be used for various purposes of industrial application. For example, they may be used to develop a novel antimicrobial agent capable of inhibiting the growth of the microorganisms or to develop an air freshener for removing offensive odor by elucidating the chemical properties of the metabolites of the microorganisms. In addition, they may be used to fundamentally remove the cause of offensive odor by providing an air-conditioning system with an environment where the microorganisms may not live.
