Background. The treatment of pulmonary nontuberculous mycobacteria (NTM) involves the long-term use of multiple drugs. Adjuvant pulmonary resection is indicated for recurrent or refractory cases if the disease is localized and resectable. However, if surgery is contraindicated due to a poor cardiopulmonary reserve or extensive disease, treatment and disease control become very difficult, and the prognosis is dismal. Following the concept of lobar collapse therapy as a new endobronchial complementary approach to treating cavitary lesions of multidrug-resistant tuberculosis in Europe, we are eagerly awaiting new approaches for managing refractory cavities of pulmonary NTM. Purpose. To clarify the safety and effectiveness of endobronchial treatment using an Endobronchial Watanabe Spigot (EWS) for managing pulmonary cavitary lesion of NTM. Methods. We conducted endobronchial occlusion for 7 refractory unresectable cavities of 5 pulmonary NTM cases (2 men, 3 women, average age 51.6 years old). The clinical, microbiological and radiological courses were followed. Results. The follow-up period was 12-33 months (median 19 months), and no serious adverse events were observed. Subjective symptoms, such as cough and sputum, were improved in all cases. Two cases achieved sputum-negative conversion and became eligible for surgery after this procedure. Four cavities respectively in 4 cases showed radiological improvement, but no cases achieved complete cavity collapse. Conclusion. Bronchial occlusion with EWS can be an effective option especially as the preoperative management in cases with refractory cavity of pulmonary NTM.