Background: Hot tub lung is a hypersensitivity pneumonitis caused by nontuberculous mycobacteria(NTM); the primary causative agent is Mycobacterium avium complex (MAC) post contaminated water exposure. Recently, 2 cases of hot tub lung were found in public bath bodyscrubbers working in Korea. However, the disease causing NTM was not identified in these cases. Here, we reported one case, along with clinical diagnostic approach to occupational medicine throughout worksite investigation. Case: A 53 year-old woman working in the public bath for 13 months’ duration developed shortness of breath. She had been cleaning the locker room, several pools and floors every day, and using scrubbers with detergent and warm water. After examination, the patient was diagnosed with hypersensitivity pneumonitis based on high resolution computerized tomography and lung biopsy. Because the Mycobacterium avium was identified in both the patient’s sputum and the warm pool, she was diagnosed with hot tub lung due to MAC. Conclusion: Hot tub lung due to MAC was confirmed in public bath housekeeper. However, few cases have been reported, even though there are many cases. To prevent damages caused by hot tub lung, general environmental management such as ventilation and cleaning is important for bath operators. Likewise, awareness needs to be increased in workers with potential NTM environmental exposure and in clinicians through education about hot tub lung in order to reduce adverse harm from misdiagnosis and mistreatment of tuberculosis.