Water extract, and methanol extract, its chloroform and hexane fractions, and estragole from Agastache rugosa O. Kuntze were tested to find the inhibition effect on the growth of several microorganisms. The organisms used were Escherichia coli ATCC 1129, Staphylococcus aureus IAM 1011, Vibrio parahaemolyticus WP, Bacillus subtilis ATCC6633, Aspergillus oryzae KFCC 890, Aspergillus niger KCCM 11240. Water and methanol extracts at the concentration of 0.5%, and chloroform and hexane fraction at the concentration of 0.05% inhibited the growth of microorganisms from 1/5 to 2/3 of the control group. Estragole identified from the hexane faction as a major component, its authentic compound completely inhibited the growth of Vibrio parahaemolyticus completely at the concentration of 0.03%, and the other bacteria were at 0.05%.