Since first reported in 1988 the Pine Wilt Disease has been established and spreaded nearly nationwide in South Korea, causing tremendous economic damage in pine forests. The pine wilt nematode (Bursaphelenchus xylophilus), causing the Pine Wilt Disease, in Korea is known to be transported by two insect vectors that are Monochamus alternatus Hope and Monochamus saltuarius Gebler. Currently the pest management strategy largely relies on pesticide application and infected tree clearing. The aim of the present study was to search for early larval parasitoids of M. alternatus using the sentinel log infested with the cerambycid eggs. Only one braconid species was collected and identified as Spathius verustus Chao. Two to ten wasp larvae attached and fed on one host larva. Parasitism rate was 55.5 to 59 % in Jinju site, while 1 to 18.1 % the other sites. Sex ratio was female-biased (female : male = 18.9 : 1). The S. verstus has potential to be use as parasitic natural enemy of M. alternatus.