Primary intestinal lymphangiectasia is a congenital lymphatic disorder characterized by dilated intestinal lacteals resulting in lymph leakage into the small bowel lumen and responsible for protein losing enteropathy. As a result, generalized edema, hypoalbuminemia, and lymphocytopenia are clinically manifested. We could not find the reason by several examinations. Therefore, we performed double balloon enteroscopy (DBE), and intestnal lymphangiectasia was diagnosed histologically by a biopsy. DBE is a safe and effective method to diagnose small bowel lymphangiectasia. We report a case of primary intestinal lymphangiectasia, which occurred in a 54-year-old male patient with generalized edema and ascites.