The ovarian development and oviposition response of two vector beetles of pine wood nematode, Monochamus alternatus and M. saltuarius, was investigated. The ovary structure of two beetles was investigated by means of light microscopy. The ovary of both beetles was composed of two ovaries that are connected by a common oviduct. Each of the two ovaries was consisted of twelve ovarioles, the functional units of female oogenesis. The ovary type was meroistic telotrophic with nurse cells and oocytes in the tropharium. Ovarian development of two vector beetles was completed at 12-14 days after maturation-feeding pine twigs. Aspect of accumulation of vitellogenins in the ovary of two vectors showed difference in developmental stages and major yolk proteins, differently from vitellogenin. To investigate oviposition performance of two vector beetles, we provided P. thunbergii and P. koraiensis bolts for egg laying and collected emerged adults from each pine bolts in the next year. M. saltuarius females made more oviposition wounds and entrance hole of larvae than M. alternatus on pine bolts. We also investigated whether two beetles can transmission of Bursaphelenchus xylophilus and the European type of B. mucronatus via oviposition to noninfected dead pines. 48-83% from newly emerged adults of two beetles were carried two species nematode. This results suggested that two species beetles can transmit nematodes through oviposition performance and transmitted nematodes successfully propagate in non-infected dead pines.