We presented a case of pulmonary alveolar microlithiasis (PAM) observed in the respiratory intensive care unit (RICU). PAM is a rare disease, characterized by the presence of calcified concretions in the alveolar spaces. Any respiratory infection may cause severe deterioration in the physiological condition, which can be evaluated as acute respiratory distress syndrome (ARDS). PAM was thought to be complicated by ARDS in this case and lung protective ventilation including low tidal volume and positive end-expiratory pressure (PEEP) was performed. We concluded that lung protective ventilation strategy is successful in PAM cases with ARDS.