Taxonomic accounts are given to the four species of Corallinaceae, Amphiroa beauvoisii lamouroux, Jania yenoshimensis (Yendo) Yendo, Serraticardia maxima (Yendo) Silva and Corallina officinalis linnaeus, collected from Ullungdo Island, Korea. S. maxima (Y endo) Silva is introduced for the first time in Korea in this study. J. yenoshimensis (Yendo) Yendo accords well with the type speciemens but is very similar to J. arborescens in outer appearance. However it is distinguished from that in height and branching pattern. C. officinalis accords well with other plants collected from Europe and Japan except for large number of medullary cell layers.layers.