The patient is a 39-year-old woman. At the age of 34, she recognized a 22 mm sized mass in the upper outer quadrant of her right breast, which was diagnosed as a fibroadenoma. 5 years later, the mass increased to 45 mm. We performed lumpectomy which led to a diagnosis of a malignant phyllodes tumor with osteogenic sarcoma. Since the resection margins were positive, we performed mastectomy in addition. Nine months after surgery, a 23 mm large mass appeared on the right fifth costal. Recurrence of malignant phyllodes was suspicious from cytological diagnosis and since thoracoabdominal CT showed no metastasis to other organs, we performed resection. Histological results were the same as the primary tumor. Two months more later, an 11 mm large mass revealed in the right anterior thoracic region. We performed resection again, which showed the same histological features as the primary tumor. Since malignant phyllodes tumors often recur in the early postoperative period, a close follow-up is recommended.