Gastric hyperplastic polyps are generally considered benign lesions, although rare cases of adenocarcinoma have been reported. Although, the underlying mechanism of carcinogenesis in gastric hyperplastic polyps is still uncertain, most malignant polyps are seen to originate from dysplastic epithelium rather than from hyperplastic epithelium. Herein, we report the case of a woman diagnosed with adenocarcinoma that originated from a hyperplastic gastric polyp that was successfully removed by endoscopic submucosal dissection. In this case, we observed adenomatous changes around the cancerous component.