Essential oil of Chamaecyparis obtusa showed antimicrobial on relatively broad spectrum of bacterial and fungal species. Staphylococcus epidermidis was highly sensitive to the essential oil but Streptococcus aureus and Streptococcus mutans were not. Vibro parahemolyticus, Pseudomoas aeruginosa and Pseudomoas putida showed sensitivity at the concentration higher that 400 ppm, Thegrowth of a pathogenic yeast Candida albicans was inhibited by the essential oil above 200ppm. The radialgrowth of several filamentous fungi was also inhibited The antifungal activity of the essential oil was effective on two plant pathogens Fusarium oxysporum and Altenaria mali. These results sug-gest that essential oil of Chamaecyparis obtusa has an antimicrobial activity by inhibiting bacterial and fungal species.