We report a case of bone marrow carcinomatosis originating from breast cancer that was treated with weekly paclitaxel (PTX). A 42-year-old female patient underwent mastectomy with axillary lymph node dissection for breast cancer in 2001. Multiple bone metastases were diagnosed in 2008, but she remained stable with chemotherapy and hormonal therapy for about two years. In 2010, thrombocytopenia occurred, and she was diagnosed with bone marrow carcinomatosis after bone marrow biopsy. She was treated with weekly PTX(80 mg/m2), and recovered successfully after treatment. About one year has elapsed since initiation of therapy, and there has been no recurrence. Bone marrow carcinomatosis originating from breast cancer is very rare, and is regarded as a disease with a poor prognosis. However, weekly PTX could be a valid treatment for prolonging survival of bone marrow carcinomatosis originating from breast cancer.