The presence of calcification in a pulmonary nodule is usually a sign of benignity. However, infrequently calcifiction can occur in a malignant lesion. Adenoid cystic carcinoma of the lung is a type of bronchial adenoma, and a rare disease. We recently experienced a case of adenoid cystic carcinoma with diffuse and homogenous calcification involving the right middle lobe associated with regional lymph node metastasis. CT examination revealed the mass to have high Housfied unit of 193, which is unusual for a maligant tumor which usually has a hounsifield unit lower than 165. From this case, it is learned that adenoid cystic carcinoma has high Hounsfield unit when it is calcified.