Metastasis of renal cell carcinoma to the oral cavity is rare. We report a case of renal cell carcinoma that metastasized to the mandible. A 60-year-old man was referred to our hospital because of spontaneous pain and swelling of the molar region of the left side of the mandible and paresthesia of the left side of the lower lip. Oral examination showed an expansile mass in the third molar region, which was covered with normal mucosa. Computed tomography (CT) demonstrated a large mass with destruction of the bone of the left mandibular ramus. The mass invaded the surrounding soft tissues. The patient had previously undergone a left radical nephrectomy because of renal cell carcinoma. In addition, he had multiple metastatic lesions in the lung. Histological examination of the mandibular tumor showed a clear cell carcinoma similar to the previous renal cell carcinoma. These findings suggested that the oral lesion was a metastatic clear cell carcinoma from the kidney. The mandibular tumor was excised to alleviate the dysphagia caused by the rapidly growing tumor. He has resumed oral intake and shown no sign of recurrence of the oral tumor as of 21 months after surgery.