A 66-year-old man who suffered from an acute exacerbation of interstitial pneumonia developed a cavitary lesion after taking immunosuppressive drugs. He was diagnosed with cytomegalovirus (CMV) pneumonia. CMV was not thought to be the underlying cause of the cavitary lung lesions, as only six cases have been described thus far. However, this case clearly demonstrates that the development of cavitary lung lesions can be caused by CMV. Following CMV pneumonia, cavitary lesions again occurred in the patient's lungs that were thought to be the first case of cavitary lesions caused by Nocardia asiatica infection.