Malignant change of the aberrant pancreas in the stomach is very rare, and there have been only 23 cases in Japan. We report a case of gastric cancer arising from the aberrant pancreas. A 46-year-old woman, who had been followed up for 7 years after a submucosal tumor of the gastric angle was diagnosed, underwent a distal gastrectomy because a gastric endoscopy revealed type 3 gastric cancer in the same region. Histological examination of the resected stomach revealed acinar cell carcinoma. There was no remarkable finding in the pancreas during the operation. In addition, there has been no case report of this histopathological type of gastric neoplasm. This case was diagnosed as one of malignant change from the aberrant pancreas in the stomach. Partial resection of the liver was performed for a solitary metastatic hepatic tumor 21 months after the gastrectomy. And interesting changes in blood levels of trypsin were observed before and after twice operations.