Two lichomolgoid copepods, Lichomolgus inflatus Tanaka and Philoconcha paphiae Yamaguti, both known very rarely since the original descriptions, are redescribed based on the specimens discovered as associates with the bivalve Dosinorbis japonicus from the Korea Strait. Lichomolgus inflatus is very closely related to L. chamarum Humes, but can be differentiated by the features of the rostrum and genital double-somite. Philoconcha paphiae is found to have an extremely variable leg armature. This is the first discovery of the two species of copepods outside the Japanese waters.