We report our experience of surgical treatment for a patient with pancreatic injury, who presented with pancreatic ascites 2 months after a blunt abdominal trauma. A 20-year-old woman was admitted to our hospital due to massive ascites and dehydration. This patient was diagnosed as having pancreatic ascites caused by the rupture of pancreatic pseudocyst, and the pseudocyst seemed to have caused by the trauma that she sustained 2 months before. As non-surgical treatment did not bring about an improvement of the patient status, she underwent cystogastrostomy. Postoperative course was uneventful and the patient was discharged on the 25th postoperative day. The patient is doing well 7 years after surgery without any signs of pancreatic pseudocyst or diabetes. A case of pancreatic ascites presenting after a significant time period following initial abdominal trauma has not been reported.