Only two species of Eurydema occur in Korea and Japan: E. dominulus (Scopoli, 1763) [= E. pulchra (Westwood, 1837), syn. n.] and E. gebleri Kolenati, 1846 [= E. rugosa Motschulsky, 1861, syn. n.]. In order to prove the above taxonomical change, we focused on three major works (1)morphology, (2)molecular identification and (3)biological experiment (inter-specific copulation, confirmation of fertilization and interbreeding). All the results of these three major works support to confirm new taxonomical change amongst these four species. The inter-specific copulation occurs (E. pulchra_male X E. gebleri_female) in nature, but the eggs from inter-specific copulation are confirmed not to be fertilized as a result of the biological experiment. A new identification key to species occurring in Korea and Japan is presented for the all stages (from eggs to adult).