Acinar cell carcinoma is a rare tumor that represents 1~2% of all pancreatic cancers. Clinical and radiologic findings are inconclusive in this disease. Acinar cell carcinoma is characterized by rapid progression and early metastasis, which lead to its poor prognosis. A 41-year-old man was admitted to our hospital for abdominal pain. Abdominal computed tomography (CT) and positron emission tomography-computed tomography (PET-CT) showed a splenic mass, which was being invaded by a pancreatic tail mass and which had increased $^{18}F$-fluorodeoxyglucose (FDG) uptake. Primary radical distal pancreatectomy and splenectomy were performed. Pathologic findings revealed an acinar cell carcinoma of the pancreas. The patient underwent a total gastrectomy three months later because of gastric recurrence. Four months later, multiple hepatic metastases were discovered, and the patient underwent a left hepatectomy. During treatment with capecitabine, there was no evidence of tumor progression for 14 months. We report a case of metastatic pancreatic acinar cell carcinoma, which did not progress for an extended period while the patient was being treated with capecitabine.