Two families of checkered beetles (Cleridae and Thanerocleridae) contain approximately 3,600 described species. Clerus is one of genera belonging to the Omadius genus-group (Cleridae: Clerinae: Clerus series), and distributed in Palaearctic, Indo-Australian and Afrotropic regions containing 17 species. Among the known species, 11 species have been recorded from Palaearctic region (seven from East Asian countries). Through a taxonomic study on the Korean Clerus species, a total of three species, C. dealbatus (Kraatz, 1879), C. pilosellus (Gorham, 1878) and Clerus sp. nov. are recognized. From the present study, it was confirmed that C. dealbatus was misidentified as Thanasimus lewisi (Jacobson, 1911) in the country, due to the similarity of the body coloration. The presence of the latter species in Korean insect fauna is very doubtful. Diagnostic characters of three Korean Clerus species are presented.