Among cases of therapy-related acute myeloid leukemia (t-AML) due to DNA topoisomerase II inhibitors, 11q23 abnormality is often detected. The usefulness of paclitaxel as a key drug in chemotherapy for breast cancer has been demonstrated. Few studies have reported t-AML due to paclitaxel. In this study, we report a patient who developed t-AML with 11q23 abnormality and bone marrow metastasis after breast cancer treatment with paclitaxel. The patient was a 61-year-old female who developed breast cancer at the age of 54 years. Four years after resection, lung and bone metastases were detected. Weekly therapy with paclitaxel at 80 mg/m2 was administered for 10 weeks (total dose: 1,200 mg), and radiotherapy was performed; thereafter, the extent of bone metastasis increased. Pancytopenia was noted 3 years after paclitaxel therapy. Bone marrow aspiration suggested AML (M4) with (11;19)(q23;p13) chromosome abnormalities. Histopathologically, bone marrow metastasis from breast cancer was detected in the same bone marrow specimen. This patient had not received any other anticancer drugs. Based on the clinical course, t-AML may have developed after paclitaxel therapy.