During the excavation to find ancient rice seeds from the peat layer (12,500-14,800 bp based on 14 dating samples) of Soro-ri, Cheongwon-gun near Cheongju city, we found not only old rice seeds, but also other organic materials including insect fossil skeletons. Although no complete specimen was found in this study, some body parts were diagnotic enough for identifying species. Among the identified insect fossils, two species were successfully identified based on their characteristic forewing morphologies, e.g., cross-ridges on forewing. The two identified species, Plateumaris sericea and Donacia flemola or near, belong to Donaciinae in Chrysomelidae, and their larvae are known to feed on the root of wetland plants, mainly in Poaceae or Cyperaceae. Such finding proved that a wetland environment was maintained in Soro-ri at that time, and was suitable for such insects to survive. Therefore, evidence from the fossilized rice seeds, together with these insect fossils, clearly proved that the environment at that time was suitable for rice, a common Poaceae species, growing.