To investigate the antifungal activity of two phytopathogens, Rhizoctonia solani and Fusarium oxysporum in vitro, chitosan oligosaccharide (MW 1,000~3,000 Da, C1K), plant compounds [Gallic acid (P-GA) and 3,4-dihydroxybenzoic acid (P-DHBA), Comps] purified from Terminalia nigrovenulosa bark, and commercial compouds (C-GA and C-DHBA) were used in this study. Also, chitosan beads were used to make mixture of chitosan oligosacchade. The EC50 values of C1K were in the range of 3,438~3,450 ppm for R. solani and F. oxysporum, respectively. Mixtures of C1K and purified and commercial two Comps strongly inhibited within 65~78% mycelium growth of R. solani after 2 and 4 days incubation. Chitosan beads (CTB) combinded with C1K had high antifungal activity against R. solani. The EC50 values of CTB combinded with C1K were in the range of 3,828~4,220 ppm. These results suggested that mixtures of C1K and Comps or CTB combined with C1K triggered as elicitors for the enhancement of suppressive activity to the phytopathogens.