We present a case of osteomyelitis of the condyle secondary to bisphosphonate-related osteonecrosis of the jaw. A 77-year-old female was referred to our clinic with complaints of swelling in the left mandibular molar regions. The patient had been suffering from myeloperoxidase anti-neutrophil cytoplasmic antibody (MPOANCA) associated vasculitis and had been treated with glucocorticoids for 8 years, and oral bisphosphonates had been prescribed to prevent osteopenia secondary to glucocorticoids. Imaging examinations showed radiolucency of the left mandibular body. Based on the diagnosis of osteomyelitis of the mandibular body secondary to bisphosphonate-related osteonecrosis, the patient received antimicrobial therapy and was well-healed. However, the patient returned 8 weeks later complaining of acute left preauricular swelling. Computed tomography showed the destructive changes in the mandibular condyle. We speculated that the infection was caused by the local spread from osteomyelitis of the left mandibular body. The risk of jaw necrosis related to antiresorptive therapy is well known. In recent years, the number of older patients being administered glucocorticoids with bisphosphonates has increased; therefore, we must be attentive to the signs of infectious diseases of the jawbone in the aging because it can easily shift to osteomyelitis or osteonecrosis and spread infection through the marrow.