Thymic hemangioma is a rare mediastinal tumor. This tumor is frequently asymptomatic and often discovered incidentally on chest radiography. This report presents a case of anterior mediastinal tumor found in a 47-year-old female patient with myasthenia gravis. The tumor was suspected to be a thymoma initially. The patient underwent extirpation for the tumor and thymus. Histopathology demonstrated the tumor was originated from the thymic tissue and composed of numerous thick- walled vascular spaces that contained multiple phleboliths. The diagnosis of thymic hemangioma was confirmed.