Monochamus saltuarius Gebler are the insect vector of the pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Buhrer) mostly in the mid-northern areas of South Korea. In 2017, we installed sentinel logs to lure efficient parasitic wasps of the vector and to evaluate ecological characteristics of parasitoids in prior to the development of biological control strategy for the PWN transmitting insect vector. As a result of the survey, we found Spathius verustus Chao (Hymenoptera: Braconidae) as a predominant parasitoid with the highest parasitism rate among six species of larval parasitoids. The parasitism rate was higher along the edge (0m of the forest depth) of the survey sites than the inner sides (20m and 40m of the forest depth). Also, the parasitoid showed highest parasitism rate in late-May at one of Gapyeong_sites, where was supposed to be the oldest infected areas. Lastly, the parasitism rate along the trap heights was higher at height of 0m than the 1.8m above the ground.