We report a case of metastatic thyroid-papillary carcinoma of the breast. A 42-year-old woman was admitted to our hospital due to palpable masses on both breasts. Past history revealed that she had three individual thyroid operations due to thyroid papillary carcinoma. The first was a left lobectomy 6 years ago, the second was a subtotal thyroidectomy 2 years ago, and the third was a excision of the neck mass due to last year's recurrence. The patient underwent mass excisions on both breasts under the impression of a benign tumor. Pathologic findings of the masses showed similar histologic findings of the thyroid papillary carcinoma and immunohistochemical stainings demonstrated that the tumors originated from the thyroid.