Diffuse panbronchiolitis is a chronic inflammatory lung disease of unknown etiology which is characterized by chronic airflow limitation and airway inflammation, predominantly localized in the respiratory bronchioles with infiltration of inflammatory cells, and has typical clinical, radiological and pathological features. Obstructive respiratory functional impairment, occasional symptoms of wheezing, and also cough and sputum resemble the feature of emphysema, bronchial asthma, or chronic bronchitis, respectively. We experienced a case of pathologically proven advanced diffuse panbronchiolitis in a 55-year-old man with productive cough and exertional dyspnea. The chest radiography showed multiple tiny nodular densities on whole lung fields. It was confirmed by thoracoscopy-guided lung biopsy and the patient was improved after initiation of treatment with low-dose erythromycin.