A 52-year-old man admitted to our hospital with a pulmonary nodule detected by chest X-ray. Painless mass was located on the right anterior chest below the right clavicle, but enlarged recently. Chest computed tomography (CT) and magnetic resonance imaging (MRI) showed the hourglass shaped mass penetrating his right 2nd intercostal muscle, and growing to intra- and extra-thoracic areas. 60 x 40 x 50 mm in size. His laboratory findings were almost within normal ranges. We performed resection of the tumor and partial resection of the 2nd and 3rd ribs with a help of thoracoscopy. Pathological diagnosis was "intramuscular lipoma-infiltrating type, no malignancy". Assistance of thoracoscopic approach was found to be useful for complete resection of the tumor existing intra- and extra-thoracic areas.