Idiopathic interstitial pneumonias are classified into acute interstitial pneumonia, cryptogenic organizing pneumonia, nonspecific interstitial pneumonia, usual interstitial pneumonia, desquamative interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, and lymphoid interstitial pneumonia. In this article, the imaging findings of each idiopathic interstitial pneumonia are described, paying special attention to the characteristic CT findings.