The genus Gonioctena Chevrolat is distributed in the Holarctic and Oriental regions, with more than 80 species. Many species of the genus have great similarity in external morphology and coloration, often cause misidentifications. Thus, the shape of the aedeagus is mainly used to distinguish closely related species. Fifty-four species, more than half of the known taxa, occur in northeastern Asia, including 18 species in the Russian Far East, 29 in China, 11 in Korea, and 18 in Japan. Among these, G. gracilicornis Kraatz (type locality: Amur) is widely distributed in Russia, China, Mongolia and Korea. However, extensive investigation on Gonioctena in Korea revealed that the Korean population of G. gracilicornis differs from that of the Russian by the coloration, the puncturation of pronotum, and the shape of aedeagus. The purpose of this study is to describe a new species of Gonioctena that was previously misidentified as G. gracilicornis. A key to Korean Gonioctena, distribution, and host plant are also provided.