The production of the entomopathogenic and phytotoxic cyclic depsipeptide beauvericin (BEA) was studied in submerged cultures of Fusarium oxysporum KFCC 11363P isolated in Korea. The influences of various factors on mycelia growth and BEA production were examined in both complete and chemically defined culture media. The mycelia growth and BEA production were highest in Fusarium defined medium. The optimal carbon and nitrogen sources for maximizing BEA production were glucose and $NaNO_3$, respectively. The carbon/nitrogen ratio for maximal production of BEA was investigated using response surface methodology (RSM). Equations derived by differentiation of the RSM model revealed that the production of BEA was maximal when using 108 mM glucose and 25 mM $NaNO_3$.