To understand microhabitat distribution of insect pest is important for developing timely management tactics. We investigated within plant distribution of Riptortus clavatus Thunberg (Hemiptera: Alydidae) eggs and its’ parasitism by egg parasitoids such as Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) in soybean fields. Sampling was carried out to determine the most preferred oviposition site (upper leaf surface, under leaf surface, pod and stem) in different varieties of soybean (Daewon, Cheongja, Taegwang, Daepung, Seomoktae, Seoritae) in Andong, 2007 and 2008. Parasitism was recorded only in 2008. In seasonal total, proportion of R. clavatus eggs deposited within soybean plant was significantly higher on under leaf surface (70-97%) followed by upper leaf surface, pod, and stem (2-29%, 0-8% and 0-2%, respectively) depending on varieties of soybean. In seasonal total, parasitism rate by O. nezarae was significantly higher on the eggs collected from under leaf surface (61%) followed by eggs collected from upper surface of the leaves (43%), pods (7%) and stem (33%). In conclusion, R. clavatus prefer upper leaf surface the most as a oviposition substrate in soybean, and highest parasitism by O. nezarae on the host eggs was also found on upper leaf surface.