Immune checkpoint inhibitors (ICIs) are now widely used to many malignant diseases, but some patients suffer from immune-related adverse events during or after ICI treatments. The monoclonal antibody infliximab is usually chosen as a salvage treatment to combat corticosteroid-resistant adverse events, but infliximab is not recommended as a response to hepatitis because of the potential risk of liver failure. An alternative treatment option has not been established. We treated a head and neck cancer patient (a 50-year-old Japanese male) who suffered from corticosteroid-resistant hepatitis during treatment with nivolumab, an anti-PD-1 ICI, and that was recovered by mycophenolate mofetil salvage therapy.