Diffuse alveolar damage (DAD) is a histological change in lung tissue, and is generally caused by an acute lung injury, which is characterized by bilateral and widespread damages. Localized DAD occurs very rarely. The causes for DAD are numerous, but the chief cause is acute interstitial pneumonia or acute exacerbation of idiopathic interstitial pneumonia, in cases of idiopathic manifestation. The 82-year-old patient, in this case study, showed a DAD lesion in only 1 lobe. The patient was otherwise healthy, with no previous symptoms of DAD. He was admitted to our medical center owing to localized infiltration, observed on his chest radiograph. Laboratory studies showed no signs of infections. DAD was confirmed by a surgical lung biopsy. The patient received corticosteroid treatment and had gradually improved. We report the case of a patient with localized, idiopathic DAD that cannot be classified as acute interstitial pneumonia or acute exacerbation of idiopathic interstitial pneumonia.