We herein report a case of cytomegalovirus (CMV) bronchitis in a 62-year-old woman with polymyositis. She presented with respiratory symptoms and CMV antigenemia while undergoing immunosuppressive therapy with methotrexate (MTX) and prednisolone (PSL). Bronchoscopy was performed, which revealed an ulceration of the left main bronchus. A mucosal biopsy confirmed CMV infection, and the patient was diagnosed with CMV ulcerating bronchitis. The administration of ganciclovir improved the lesion, and the CMV antigenemia disappeared. Endobronchial ulceration should be considered in the differential diagnosis of CMV disease.