Heterotopic pancreas (HP) is a rare entity, defined as pancreatic tissue without a true anatomical or vascular connection to the pancreas. Gastric HP often has nonspecific clinical symptoms and is usually detected in the gastroscopy. Its diagnosis by gastroscopic biopsy is difficult as the lesion is mostly located in the submucosa. Its clinical diagnosis depends on ultrasonographic endoscopy and pathologic biopsy after endoscopic treatment. HP is sometimes surgically resected because it can be difficult to distinguish HP from neoplastic submucosal masses such as gastrointestinal stromal tumors. Although not common, HP should be given due consideration in the differential diagnosis of extramucosal gastric masses to avoid unnecessary intervention. We reported a case of gastric HP that was found incidentally as a gastric mass on gastroscopy.