Müllerian inhibiting substance (MIS) is a protein that encoded by MIS gene. It has also been called Müllerian inhibiting factor (MIF) and anti-Müllerian hormone (AMH). Mis expression occurs in ovarian granulose cells of females postpartum, and serves as a molecular biomarker for relative size of the ovarian reserve. In humans, the number of cells in the follicular reserve can be used to evaluate the reproductive function and fertility of female. Pagrus major is typical cultured fish in Korea but there is no clear evidence for their gene identification. However, in many teleost, MIS genes were demonstrated already. Present study aimed to identify the Mis gene in Pagrus major and seasonal difference of its expression. Using conserved sequence of the other known teleost Mis genes, we make conserved primers. Pagrus major’s ovary samples were obtained from the sea rim farm (Geoje, Korea) and kept in RNAlater®Solution or fixed in 4% paraformaldehyde containing 0.16% picric acid. RNA was isolated from kept sample and cDNA was synthesized. The PCR products were performed ligation with TOPO vector and transformation in TOP10 cell and sequenced the Mis mRNA fragment. MIS was localized in the follicle cells. Its mRNA levels were higher in summer than spring or fall. Based on them, it is suggested that MIS can be used to estimate the fertility of this fish.