Schwannoma is a common mesenchymal neoplasm; however, adrenal schwannoma is rare, and it is frequently misdiagnosed as adrenal cortical adenoma. We herein report a 91-year-old Japanese man with right adrenal schwannoma that was pathologically diagnosed after adrenalectomy. To our knowledge, this is the first case of adrenal schwannoma in the oldest patient and with the longest follow-up period reported, including radiological images from 10 years earlier.