A case of traumatic pancreatitis with subsequent joint pain and osteolytic lesions is presented. A 10-year-old girl was admitted to our hospital with abdominal pain caused by blunt epigastric injury. She was diagnosed with traumatic pancreatitis, and multiple pancreatic pseudocysts subsequently developed. Two weeks after admission, she complained of joint pain, and MR revealed osteolytic lesions of both knee joints. On the 58th day, endoscopic transgastric pseudocyst drainage was performed. Joint pain and osteolytic lesions resolved rapidly, in parallel with the decrease in serum amylase level and pseudocyst size.