Antifungal activities of trans-cinnamaldehyde (CA) derivatives including commercial CA derivatives as well as synthesized CA derivatives against various human pathogenic fungi were investigated. Among the derivatives tested, -chlorocinnamaldehyde, $alpha$-bromocinnamaldehyde and 7-phenyl-2,4,6-heptatrienal were more potent than CA in antifungal activity, $alpha$-Bromocinnamaldehyde was the most effective in inhibiting the growth of representative fungi of dermatomycosis with minimum inhibitory cocentration(MIC) of 0.61~9.76$mu extrm{g}$/ml . In the structure-activity relationship, introduction of the chlorine and bromine group into the C-2 of CA resulted in the decrease of MIC. Derivative with more double bonds exhibited the increase of antifungal activity against various pathogenic fungi.