A 67-year-old woman underwent abdominal ultrasonography as part of a general health examination and was incidentally found to have a mass 5 cm in diameter in the left adrenal gland. She had no experience of abdominal trauma. Computerized tomography (CT) revealed a 5.5 x 5.0 cm mass in the left adrenal gland, which was heterogeneously enhanced by the contrast medium. Hormanal data for adrenal function were all within the normal range. For the suspected non-functioning adrenal tumor, the patient underwent adrenalectomy. Histopathological examination demonstrated only hematoma without tumor cells.