Arteriovenous malformation (AVM) of the stomach is extremely rare. We report a patient with asymptomatic gastric AVM detected during mass screening of the upper gastrointestinal tract. The patient, a 69-year-old female, had no history of gastrointestinal bleeding. Endoscopy revealed a gastric submucosal tumor (3 cm in diameter) at the posterior wall below the esophago-cardiac junction. Endoscopic ultrasonography (EUS) showed a hypoechoic structure in the third layer of the stomach, suggesting gastric AVM in the submucosal layer. Complete resection of the AVM tissue was performed by strip biopsy with surgical resection. Histological examination showed AVM in the submucosal layer. EUS examination was useful for the diagnosis of gastric AVM in this case.