A 68 years old man was referred to our hospital with symptoms of hematemesis and melena. An emergent gastroscopy showed a gastric ulcerative lesion with an exposed vessel (Forrest IIa) protruding from its base, which was located at the posterior wall of the upper portion of the gastric body. Endoscopic hemostasis was performed with endoclips and antiulcer treatment was done. Although the ulcerative lesion was healed two months after endoscopic hemostasis, the histopathological examination of the biopsy specimens revealed well differentiated adenocarcinoma (0-IIc). The tumor could be resected en-bloc by endoscopic submucosal dissection (ESD) without any complications such as perforation or postoperative bleeding. The resected specimen showed that the resected tumor was well differentiated intramucosal adenocarcinoma (13 x 10 mm) with a clear lateral margin. There was no recurrence during 12 months follow-up after ESD treatment. Follow-up endoscopy with biopsies should be performed for accurate diagnosis of gastric ulcerative lesions and ESD after endoscopic hemostasis with endoclips was an effective method for early gastric cancer presenting with massive hemorrhage in our case.