During a study of harpacticoid copepods from Korea, one species of the family Orthopsyllidae was found by rinsing macroalgae collected from the intertidal and subtidal zones at Hangaechang, Munseum Islet in Jeju Island of Korea. The Orthopsyllus is closely related to Orthopsyllus linearis curvaspinata Mielke, 1993, however it is distinguished from the original description by the combined characters of slightly slender caudal seta V in the female, relatively short and ovoid caudal ramus, the seta formula of P3, and the length of P2 and P4 endopod in the male. Since Orthopsyllus linearis (Claus, 1866) is notorious for its incomplete previous descriptions and therefore its polymorphic status, it is premature to fix the status of present Orthopsyllus species from Korea, without the detailed comparative study among the congeners. However due to the urgent need for the report of the genus in the region, we report this species as Orthopsyllus linearis (Claus, 1866) like but different one within the genus: Orthopsyllus cf. linearis (Claus,1866). This is the first report of the genus Orthopsyllus for the first time in Korea.