A pagurid crab carrying half of a bivalve shell was collected from Jejudo Island and identified as Porcellanopagurus nihonkaiensis. A diagnosis with illustrations of this specimen is presented. Although, Komai and Takeda (2006) reported this species as rare and known only from Japan, its range is now extended to Korean waters. At present, it is the only species of the genus Porcellanopagurus represented in Korean waters.