The patient was a 41-year-old woman who was a long-term resident in a psychiatric hospital for schizophrenia. She was referred for closer examination of an abnormal shadow on the chest. The irrigation fluid was cloudy on bronchoscopy. Elevated serum antigranulocyte-macrophage colony-stimulating factor antibodies and the pathology findings on transbronchial lung biopsy led to the diagnosis of autoimmune pulmonary alveolar proteinosis. Whole lung lavage (WLL) was performed under general anesthesia because of the progression of hypoxemia. At the time of WLL, high-frequency chest wall oscillation was used to achieve chest wall vibration, which was safely and successfully performed. The high-frequency chest wall oscillation method can be useful as an option for performing mechanical percussion. We present a case of autoimmune alveolar proteinosis in which whole lung lavage was performed via a sputum-assisting device using high-frequency chest wall oscillation.