In order to obtain leading compound for the development of new pesticide through the organic synthesis of natural products, the synthesis of ricinine, an active compound of Ricinus communis, was established and biological activities of synthetic compounds against insects were examined. The synthetic scheme of ricinine was composed of four steps by the spontaneous condensation of the cyanoacetyl chloride. A modified synthetic process was also estabilshed to enhance the synthetic yield by simple cyclization of ethoxymethylene malononitrile. In the bioassay results of synthetic ricinine and intermediates on four insects, the mortality of ricinine on brown planthopper (BPH, Nilaparvata lugens) and pea weevil(PW, Bruchus rufimanus) was 80% and 75% at the concentration of 1,000 ${mu}g/ml$ respectively. Chloronorricinine and chlororicinic acid having chloride group in molecular structure gave 60% mortality on two-spotted mite (TSSM, Tetranychus urticae) at the concentration of 500 ${mu}g/ml$. The mortality of compounds on house mosquito (HM, Culex pipens pallens) was meager at 10 ${mu}g/ml$ level.