Renal cell carcinoma (RCC) is capable of metastasizing to several organs. Synchronous isolated contralateral adrenal metastasis of the primary RCC is, however, very rare. Herein we report a case of RCC with a huge solitary metastasis to the contralateral adrenal gland that was surgically treated. We scheduled nephrectomy for the left primary RCC and adrenalectomy for the right adrenal tumor. However, at surgery we found a huge right adrenal tumor that had invaded the right kidney, right renal vein, and inferior vena cava. Therefore right nephrectomy was performed simultaneously with resection and reconstruction of the inferior vena cava. Pathological findings demonstrated that the left renal tumor and right adrenal tumor had the same histology. Although the patient required hemodialysis, he remains well at six months postoperatively. So far, there have been only two cases of a solitary contralateral metastatic adrenal tumor that was larger than the primary RCC, thus the present case is the third one.