A case of substernal goiter is reported. A 78-year-old female was admitted to our hospital with no symptoms. Chest roentgenography on admission showed that a mass of 3 by 5 cm in size with calcification located in the substernal region. Computed tomography of the chest and aortography revealed that the mass was attached to the trachea, but the connection to the great vessels was not clear. Pathological findings of the incisional biopsy specimen showed thyroid tissue with no evidence of malignancy. Our clinical diagnosis was substernal goiter. Surgery was not carried out in this case, based on the literature. Surgery is indicated in case of malignancy or in cases with severe illness such as respiratory disorder and superior vena cava syndrome.