Angiosarcoma is a malignant mesenchymal tumor characterized by the presence of vascular endothelial cells. Although rare, angiosarcoma developing in the mammary glands has a poor prognosis. We report a case of breast angiosarcoma with a preoperative diagnosis of late recurrence of breast cancer. A 78-year-old woman noticed a tumor in her right breast and visited our hospital. The patient had undergone breast-conserving surgery and axillary lymph node dissection from the right breast 12 years before the visit. The tumor was diagnosed as T4bN0M0, stage IIIB. Anastrozole was administered as postoperative adjuvant therapy for 5 years; the patient also received 50-Gy whole-breast radiation therapy after surgery. Physical examination during her visit revealed an elevated lesion with blue purpura around the nipple in the right breast. We performed breast ultrasound and detected a well-defined 19.6 × 16.4 × 10.7 mm hypoechoic tumor in the left subareolar area. The patient underwent core needle biopsy (CNB). Based on the CNB specimen findings, she was suspected to experience late local recurrence after surgery. Therefore, she underwent total mastectomy after breast-conserving surgery. A dark-red tumor sized 18 × 12 mm was found in a specimen from the nipple. The pathological diagnosis of the specimen revealed short spindle-shaped tumor cells with strong nuclear pleomorphism and a significant interstitial fibrosis. Immunohistochemistry using D2-40 and CD31 antibodies showed irregular luminal proliferation at the anastomosis, infiltration into the surrounding tissue, and massive necrosis, thereby leading to the diagnosis of breast angiosarcoma. We have reported a case of breast angiosarcoma with a preoperative diagnosis of late recurrence of breast cancer.