Synovial sarcoma (SS) is a highly malignant tumor that accounts for 10% of all soft-tissue sarcomas. Primary SS arising from the lung is extremely rare, and the prognosis is poor. We report a case of pulmonary SS presenting with a mass lesion invading the right upper and middle lobes, extending to the mediastinum and the chest wall. After tru-cut biopsy, surgical resection was performed. The final diagnosis was SS (biphasic type) based on histological and immunohistochemical findings. There are no guidelines for optimal treatment due to the rarity of these tumors. Current treatment includes surgery and adjuvant chemotherapy and/or radiotherapy.