We report a case of gastric adenoma which was found incidentally on $^{18}F$-FDG PET/CT study for cancer screening in asymptomatic patient. It showed focal and intensely increased. FDG uptake in the antrum of stomach. On the gastroduodenoscopy, it showed flat elevated lesion with irregular margin. Histologically, the lesion was confirmed gastric adenoma with high grade dysplasia and removed by endoscopic mucosal resection.