We present a case of a 55-year-old woman who visited our hospital aware of a lump in her right breast. We diagnosed it as bilateral breast cancer [Rt: ABCDE, T3N1M0, ER (-), PgR (-), HER2: 3+, Stage IIIA; Lt: C, T2N0M0, ER (-), PgR (-), HER2: 1+, Stage IIA]. She underwent NAC with EC followed by docetaxel. After cPR, an operation (Rt Bt+Ax, Lt Bp+Ax) was performed. Liver metastases were identified 9 months after the operation, and she was administered weekly paclitaxel+trastuzumab for 12 courses. After cPR, the treatment was changed to trastuzumab only. Because a cerebellar metastasis appeared in postoperative month 19, she underwent an operation using a gamma-knife. Because a new cerebellar metastasis appeared in postoperative month 26, she underwent another gamma-knife operation. Furthermore, liver metastases were diagnosed as PD, and treatment was changed to vinorelbine and trastuzumab. Because third new cerebellar metastasis appeared in postoperative month 45, she underwent another gamma-knife operation. Lung metastases were identified 59 months after the operation, and the therapy was changed to lapatinib and capecitabine. There was no subsequent growth of metastatic tumors, and good control was obtained.