Mixed squamous cell carcinoma and papillary carcinoma in the thyroid gland is a very rare malignant tumor. Primary squamous cell carcinoma of the thyroid may develop from squamous metaplasia of the follicular epithelium in a variety of pathologic conditions, such as other differentiated carcinomas of the thyroid. A 70-year-old man presented with a palpable mass on the right side of the thyroid gland. The patient underwent a right lobectomy without neck lymph node dissection. Histopathological findings revealed primary squamous carcinoma mixed papillary thyroid carcinoma. He underwent a completion thyroidectomy and radioactive iodine therapy. Adjuvant radiotherapy and chemotherapy were not performed.