This study is focused on finding new natural materials that have antimicrobial activity. We found that 3 plants extracts, Magnolia sieboldii K. Koch (M. sieboldii K. Koch), Rhus chinensis (R. chinensis) and Metasequioa glyptostroboides (M. glyptostroboides), have antimicrobial activities by disk diffusion method. We determined the Minimum Inhibitory Concentation (MIC) of each and found that 0.3 ∼ 0.35 % of M. glyptostroboides essential oil and 0.35 ∼ 0.4 % of M. sieboldii K. Koch extracts inhibited fungal growth and 0.45 ∼ 0.5 % of R. chinensis extracts inhibited bacterial growth. We isolated compounds from extracts and verified what have antimicrobial activity. As a result we found that caryophyllene oxide and caryophyllene isolated from M. glyptostroboides, costunolide and dehydrocostus lactone from M. sieboldii K. Koch and ethyl gallate, ethyl-3-gallate from R. chinensis have antimicrobial activities. In accordance with antimicrobial activity, O/W cosmetic emulsion containing mixture of 3 plants extracts showed preservative efficacy against both bacteria and fungi. Based on the above data we suggest that extracts from M. siebodii K. Koch, R. chinensis, and M. glyptostroboides, replace chemical synthetic preservatives and be applied as a natural preservative.