A 63-year-old female was admitted to our hospital with chief complaint of exertional dyspnea. Right massive pleural effusion was found. After chest drainage was performed, chest CT scan and MRI showed several masses in the anterior mediastinum and on the diaphragma. Mesothelioma was suspected for needle biopsy. Pleuropneumonectomy with combined resection of diaphragma, superior vena cava and pericardium was performed. Histologically, the Tumor was mixed thymoma. She is well and alive for three years after operation. Pleuropneumonectomy may be a choice of effective treatments for invasive thymoma with pleural dissemination.