Enzymatic polymerization of cardanol, a phenol derivative mainly having a C15 unsaturated hydrocarbon chain with 1-3 double bonds at m-position, and curing of the resulting polymer have been examined. Soybean peroxidase catalyzed the oxidative polymerization of cardanol to give an oily, soluble polymer under appropriate reaction conditions. NMR and IR analysis of the product showed that only the phenolic moiety was polymerized and the carbon-carbon unsaturated group in the side chain of cardanol was not reacted during the polymerization. The polymer was subjected to the hardening by cobalt naphthenate catalyst, giving a crosslinked tough film. The curing process was monitored by FT-IR spectroscopy.