Until now, there were no records of fossil ants both types of amber or impression in Korea, despite many fossil ants were known from Japan and China. Majorities of extinct fossil ants were mainly distributed from the Eocene to Miocene strata in worldwide. In Korea, the ant fossils were discovered only from a single site, the Pohang basin which is the typical Neogene sedimentary basin. Duho Formation, which new fossil species was found, belongs to Pohang basin and ranges from about 150m to 200m in thickness. More than 10 unidentified species of ant fossils excavated from Duho Formation were recognized as Formicidae by the authors. Hence, we provided short descriptions of one new fossil species, Aphaenogaster koreana sp, nov. and introduced current status of Cenozoic fossil ants excavated from Duho Formation, Republic of Korea.