Spontaneous hemothorax may be developed as a complication of von Reckilnghausen's disease. It is rare but fatal. A 60 year old man with von Reckilnghausen's disease was admitted to our hospital because of left chest and shoulder pain. Radiograph of chest showed a massive left pleural effusion. Thoracentesis revealed gross blood. The peripheral angiography was done to determine the source of bleeding and its finding showed intercostal artery aneurysm in left 7th rib. No active bleeding from the aneurysm was seen. The source of the hemothorax was believed to be hemorrhage from rupture of intercostal artery aneurysm. He was inserted chest tube and treated embolization of intercostal artery aneurysm.