We report a case of uterine metastasis of the breast cancer. The patient was diagnosed with invasive ductal carcinoma of the breast and underwent partial right mastectomy and sentinel lymph node biopsy. Tamoxifen was administered as adjuvant endocrine therapy. Four years after the surgery, she had irregular genital bleeding, and was referred to our hospital for cytological diagnosis of uterine cancer. Postoperative pathological diagnosis showed uterine metastasis of breast cancer, and it was decided to treat the recurrence of breast cancer with aromatase inhibitors and CDK4/6 inhibitors, a molecular targeted therapy. The patient has been progression-free for 5 months.