The patient was a 47-year-old man who had been found to have an intrathoracic lipoma arising from the left chest wall during a routine physical examination 4 years previously, and had been followed-up. He visited our hospital because of left chest pain. Since the tumor had enlarged, he was scheduled for surgery. He developed pneumothorax before surgery, and imaging studies confirmed the presence of a pedunculated growth. It was easy to perform thoracoscopic resection of the tumor, which was diagnosed as lipoma by pathology. The patient is free of recurrence 2 years after surgery.