A 48-year-old woman was admitted for surgery on a lung tumor found incidentally. Her medical history showed a synovial sarcoma of left inguinal region which was resected 12 years ago. We performed segmentectomy of left S4 + 5 to removed the metastatic tumor. Histological examination revealed that the tumor was metastatic synovial sarcoma. Synovial sarcoma can metastasize to lung frequently but such a long disease free interval as 12 years is quite uncommon.