The existence of a lung cavity on chest radiographs suggests the presence of lung disease, including benign or malignant disease. Lung cancer, tuberculosis, and fungal infection are all known for developing lung cavity. In addition, there are some characteristic findings in the differential diagnosis of cavitary disease, although these cavitary diseases often coexist. Here, we report two cases that presented cavitary lung cancer with concomitant chronic infectious disease. One patient showed pulmonary aspergillosis and lung adenocarcinoma, the other patient showed Mycobacterium avium complex lung disease and lung adenocarcinoma. These chronic infectious diseases develop slowly, and clinicians often follow up over several months. To reduce the delay in diagnosis of malignancy, clinicians should aggressively collect the specimens from cavitary lesions and make a correct diagnosis when encountering lung cavity in diagnostic clinical imaging.