Chondrosarcoma is the second most common bone sarcoma, for which complete resection is the only effective treatment. Herein, we report a case of completely resected rib chondrosarcoma protruding through the bone marrow. An intramedullary lesion was revealed with magnetic resonance imaging using short inversion time inversion recovery sequence (STIR-MRI), but was not depicted by computed tomography. STIR-MRI is highly sensitive for the detection of bone tumors due to the suppression of peritumoral soft tissue signals, and is critical for radical resection of chondrosarcoma.