Polycarbonate was decomposed into phenol, bisphenol A and p-isopropenylphenol by the reaction at 130-300 degrees C in water. The decomposition reaction was accelerated by the addition of Na2CO3, and the yield of identified products reached 68% in the reaction at 250 degrees C for 1 h. By using the decomposed products, the prepolymer of phenol resin was synthesized.