Aster pseudoglehni, formerly misidentified as A. glehni or A. glehni var. hondoensis in Ullung Island, Korea, is described and illustrated. This species is most similar to but differs markedly from A. ageratoides by petiolate median leaves with 8-20 pairs of serrate teeth and multinerved veins, and compact corymb-like capitulescences consisted of more than 40 heads.