Sclerosing encapsulating peritonitis (SEP) is a rare cause of bowel obstruction. It is difficult to diagnose and the prognosis is poor. This report describes a case of SEP after living donor liver transplantation that was successfully treated with tamoxifen. A 56-year-old male, that had received a liver transplant for hepatitis C virus-related hepatocellular carcinoma 5 years earlier, was admitted with continuous abdominal pain and nausea. He had increased C-reactive protein levels and white blood cell count, and underwent laparotomy 5 days after hospitalization. The surgical findings showed ascites and SEP of the small bowel. An attempt to peel off the adhesions was stopped because there was a strong risk of intestinal tract damage. Tamoxifen treatment was initiated for SEP after surgery. The patient's symptoms gradually improved and he was able to resume feeding. He had been symptom-free for over 3 years at the last follow-up.