The incidence of fungal infection is increasing due to wide use of antibiotics, steroids, chemotherapeutic agents and immunosuppressive agents. Aspergillus is a common fungi in the atmosphere and the most common organism of fungus involving the external auditory canal. It sometimes involves the paranasal sinuses, but rarely involves the middle ear cavity and mastoid antrum. Recently, the authors experienced a case of aspergillosis in the mastoid antrum which was confirmed postoperatively by biopsy. Good postoperative results were obtained with radical mastoidectomy and antifungal agent use. We report this case with a review of the literature.