Volatile essential oils obtained by steam distillation from 55 plant parts of 42 species of representative aromatic plants newly collected in Korean peninsula have been evaluated for antimicrobial activity against 5 microorganisms. The essential oils derived from 15 plant parts and 9 plant parts were found to exhibit very strong antimicrobial activities by more than 95% inhibition at 100 ${mu}g/ml$ against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Essential oil components such as l-limonene, ${eta}-myrcene$, linalool, ${gamma}-terpinene$, ${alpha},{eta}-phellandrene$, 1,8-cineole, l-borneol and bornylacetate, as a whole, have primarily contributed to the manifestation of the antimicrobial activity.