Aspergillosis of the bone is rare and resistant to treatment. We report a case of Aspergillus infection of the masticator space including mandibular bone in a diabetic adult. After extraction of a posterior tooth, the patient began to suffer from facial pain. The pain worsened in spite of antibiotic treatment. The results of serum tests and biopsy showed an invasive aspergillosis of the left masticator space including the mandibular bone six months after the onset. Although invasive aspergillosis can be fatal, the infection in our case responded to itraconazole treatment. Even in diabetes mellitus, invasive aspergillosis may occur after surgical interventions such as tooth extraction.