Baculovirus expression system has been used to produce functional proteins of various eukaryotic genes. A polydnaviral gene, CpBV-ELP1, was cloned in an alpha-baculovirus, Autographa californica multiple nuclear polyhedral virus (AcNPV), and expressed in Sf9 cells. CpBV-ELP1 protein was released into the culture medium due to its signal peptide. The culture broth containing CpBV-ELP1 was collected and fractionated with different concentrations of ammonium sulfate. Most CpBV-ELP1 was precipitated in 25-100% ammonium sulfate. The precipitate proteins were separated with a size exclusion chromatography sieving 100 kDa size. CpBV-ELP1 was eluted after relatively high molecular weight protein peaks. The fractions rich in CpBV-ELP1 were collected and further fractionated with an anion exchange chromatography. The purified CpBV-ELP1 was toxic to both larvae of Plutella xylostella and Spodoptera exigua by oral test used as leaf dipping method. A lethal median concentrations (LC50) were 7.5 ㎍/mL (95% CI: 1.2-24.3 ㎍/mL) for 2nd instar larvae of P. xylostella and 4.4 ㎍/mL (95% CI: 1.9-8.4 ㎍/mL) for 3rd instar larvae of S. exigua. These results suggest that CpBV-ELP1 may be applied to develop novel transgenic crops.