We report a case of emergency resection of a giant gastrointestinal stromal tumor of the stomach associated with hemorrhagic shock. A 79-year-old woman was admitted to our hospital because of massive hematemesis. Laboratory analysis revealed a hemoglobin level of 6.5 g/dL. Abdominal computed tomography (CT) and upper gastrointestinal endoscopy revealed a submucosal tumor, 12 cm in diameter, in the fornix of the stomach. As a Dieulafoy-like lesion was present, we attempted coagulation hemostasis in the exposed blood vessels. Endoscopic hemostasis was not successful. The patient went into hemorrhagic shock. Emergency surgery was performed: total gastrectomy with distal pancreatosplenectomy. The resected specimen measured 10×12×7 cm and was hard. Immunohistologically, the tumor was positive for c-kit and CD34 and negative for alpha smooth muscle actin (αSMA), desmin, and S-100. Histological examination revealed that the patient had a high-risk gastrointestinal stromal tumor of the stomach with no nodal metastasis. The postoperative course was uneventful and the patient has remained alive without recurrence for 4 years.