A new bitterling, Acheilognathus majusculus is described from 20 specimens collected from the Somjin and Nakdong River, Korea. The new species is similar to Acheilognathus yamatsutae, but distinguished from the latter and congeners by the combination of the following characteristics: 15-21 gill rakers, 37-40 vertebrae, longer barbel, greenish body coloration, nuptial color of males and slightly protrusive snout. A key to species of Acheilognathus from Korea is included.