Chondrosarcoma of rib origin is rare. A 50-year-old man without symptom was pointed out an abnormal shadow on chest X-ray. Computed tomography (CT) showed a low density mass arising from the right chest wall, and a CT-guided needle aspiration biopsy disclosed the tumor consisted of cartilage matrix with a partial necrosis. We suspected the tumor to be a chondrosarcoma of rib origin and performed a wide resection with the right 3rd and 4th ribs. The defect of the chest wall was repaired with double prolene mesh. Histological examination revealed grade 2 chondrosarcoma. Postoperative course has been uneventful for 25 months.