A 53-year-old male was admitted with cough and chest pain. A chest X-ray film showed left pleural effusion and a chest CT revealed irregular thickening of the pleura. Pleural fluid cytology and percutaneous needle biopsy were negative for malignancy. Thoracoscopic findings revealed fibrin network with pleural effusions and yellow-white pleural thickening, but neither nodules nor masses were found. The thoracoscopic biopsy specimen from the pleural thickening resulted in the diagnosis of malignant pleural mesothelioma. Left pleuropneumonectomy with mediastinal lymph node dissection was performed. Since detailed inspection of the pleural cavity and taking large biopsy samples under thoracoscopic examination are possible, we consider thoracoscopic biopsy to be a useful method for obtaining diagnosis of malignant pleural mesothelioma. Pleuropneumonectomy and systematic lymph node dissection of the pulmonary hilum and mediastinum were believed to be necessary for the surgical treatments.