To isolate plant insecticidal factors, a series of survivorship tests were conducted using artificial diets mixed with seed extract of a mungbean variety (Vigna radiata), which gave a high mortality to the bean bug, Riptortus clavatus. Seed flour was extracted with methanol and ethanol solutions, and then the crude extract was first fractionated with layers of ether, n-butanol and water in solvent/solvent partition. Layers of ether and n-butanol fractions showed insecticidal effects to the bean bug, respectively. The n-butanol fraction was further isolated with several fractions on a reversed-phase column chromatography, and its 100% methanol fraction showed a high insecticidal effect. The fraction was further isolated on a normal-phase column chromatography, and the 70% methanol fraction showed the highest insecticidal effect. The final fraction was analyzed and fractionated on a reversed-phase HPLC. The active isolates were almost insoluble in any organic solvents and did not show any absorption in ultra-violet and visible light wavelength range. On the other hand, the ether fraction of crude extract was isolated on a normal phase column chromatography, and its hexane fraction showed the activity. The hexane fraction was further isolated on a reversed-phase HPLC and tested for the survivorship of the bean bug.