Chondrosarcoma of rib origin is rare in Japan. We treated two cases of chondrosarcoma of rib origin. Case 1: A 68-year-old man with anterior chest wall mass and chest pain was underwent aspiration biopsy in Inami General Hospital. The histological examination showed Class V. Operation was done in our department and the histological diagnosis was chondrosarcoma. The tumor was 30 x 20 x 20 mm in size arising from the left fourth rib. The defect of bony chest wall was repaired with a double layer of Marlex mesh. His postoperative course was uneventful. Case 2: 66-year-old man noticed a tumor in left anterior part of the chest 7 months ago. He was underwent incisional biopsy and the histological diagnosis was chondrosarcoma. Radical resection was performed. The tumor was 70 x 50 x 50 mm in size arising from the left rib. His postoperative course was uneventful.