A 79-year-old man was admitted our hospital because of severe abdominal fullness. An abdominal ultrasonography showed a large amount of ascites, and diagnostic puncture detected chylous ascites. An abdominal computed tomography revealed a large amount of ascites and a multinodular mass with calcification in the mesentery of the small intestine. An infectious disease, such as tuberculosis, or malignant tumor was suspected to be the causative disease, but there was no diagnostic evidence in further examinations. Based on clinical features, imaging data and chylous ascites, we searched for case reports and found two similar cases of mesenteric panniculitis. Mesenteric panniculitis was highly suspected in this case, however, histopathological examination was rejected by patient. Therefore, we treated with steroid therapy, which had been reported as effective therapy, and the ascites decreased without recurrence.