We present a case of a 47-year-old woman with benign solitary fibrous tumor of the pleura originated in the diaphragm which was discovered incidentally on a chest radiograph. Chest radiograph, sonograph, computed tomographic scan and magnetic resonance image studies proved a well circumscribed and lobulated fibrous tumor of the pleura. During the subsequent right thoracotomy, the tumor was found to be encapsulated and consisted of firm mass. It was connected to the diaphragm with $5{ imes}4$cm area by pedicle. Most of the tumor was free of adhesion. It was excised completely together with attached diaphragm. The tumor measured $23.5{ imes}13.5{ imes}8.0$cm and the pathologic diagnosis was benign solitary fibrous tumor and the attached diaphragm was free of disease.