Immune checkpoint inhibitors (ICIs) significantly prolong survival in patients with metastatic melanoma but can lead to serious immune-related adverse events. In this report, we described a case of atypical neuropathy caused by nivolumab plus ipilimumab combination therapy before primary tumor resection. In our case, not only demyelinating neuropathy, but also muscle weakness and unilateral facial nerve palsy developed and manifested as severe and diverse symptoms. Moreover, unlike spontaneously developing demyelinating peripheral neuropathy, the present case suggested the therapeutic effects of high-dose methylprednisolone monotherapy for the treatment of ICIs-induced immune-related demyelinating peripheral neuropathy.