The structure of the decomposition products (LMC: low molecular weight chitosan) was characterized by FT-IR analysis. The structure and molecular weight of FLMC, prepared from the decomposition products by modification with furfuryl glycidyl ether, were characterized by 1H NMR and GPC analysis, respectively. F-LMC was initially water-soluble, but after the exposure to visible light, it became water-insoluble, indicating that F-LMC undergoes visible lightinduced inter- and intra-molecular cross-linking. The cross-linking was determined by concentration of F-LMC and time of exposure to visible light. The cytotoxicity test using fibroblast 3T3 showed no toxicity of F-LMC. Cross-linked F-LMC surface inhibited cell adherence.