Pulmonary alveolar proteinosis is characterized by the accumulation of PAS positive lipoproteinaceous or amorphous proteinaceous material in the alveolar space with spared delicate septal architecture of the lung interstitium and impaired gas exchange of alveoli. We experienced a case of secondary pulmonary alveolar proteinosis in a 41 year old male patient who have occupational history of engagement as a mason over 4year. He compalined exertional dyspnea and chest discomfort, and presented fine inspiratory crackle at both lower lung field, numerous fine nodular denisties in both lung field with peripheral sparing. Light microscopic finding of lung tissue obtained by transbronchial lung biopsy revealed homogenous eosinophilic colloid-like luminal content in the alveolar space, and electron microscopy of bronchoalveolar lavage fluid concentrate showed electron-dense multilamellated structures. To treat the disease, we tried whole lung lavage of right lung with isotonic saline under general anesthesia. After whole lung lavage of right lung, he showed markid improvement of symptom and partial improvement of chest X-ray findings. The patient has been followed for 12 month until now, with no evidence of aggravation