Allergic bronchopulmonary aspergillosis (ABPA) is an allergic reaction caused by the fungus Aspergillus, and it is often treated with steroids or antifungal agents. However, long-term use of these medications can lead to infections and drug interactions. We present the case of a 71-year-old woman with ABPA who was diagnosed with hepatitis B and active hepatitis C, and sputum analysis revealed the presence of bacteria. Oral steroids were initially administered, but the patient was switched to mepolizumab because of numerous infectious complications. The early introduction of mepolizumab is effective in patients with ABPA complicated by infectious diseases.