Recently, bisphosphonate and denosumab have been widely used for the treatment of bone metastasis of breast cancer. However, medication-related osteonecrosis of the jaw(MRONJ)has often been reported as a side effect of these drugs. We experienced a rare case of intracranial epidural abscess secondary to MRONJ. The patient died of the condition, although chemotherapy was effective. The mechanism of and therapy for MRONJ have not been clarified; therefore, its prevention should be emphasized.