The antifungal activity of chitosan (M.W. 400,000~500,000) and chitooligosaccharide (M.W. 3,500~5,000) was investigated against Candida albicans and Trichophyton rubrum. Chitosan showed antifungal activity against C. albicans and T. rubrum at 50 and 100 ng/ml, respectively while chitooligosaccharide did not suppress the growth of fungus. The mode of antifungal activity of chitosan was found to be fungicidal activity. In order to investigate the induction of apoptosis by chitosan, exposure of phosphatidylserine on the surface of the cytoplasmic membrane was observed by the FITC-annexin V reaction. The results showed that chitosan induced apoptosis on C. albicans.