Immune checkpoint inhibitors (ICIs) have been developed as cornerstones of cancer therapy, but the growing use of ICIs has induced immune-related adverse effects (irAEs). Immune-related colitis, which is one of the most common irAEs, generally occurs 2-4 months after ICI treatment initiation and can be life threatening. Therefore, early diagnosis and appropriate management are required. A rare autopsy case of nivolumab-related severe colitis that occurred 34 months after the start of treatment and recurred despite temporal remission with corticosteroids and infliximab is presented. Physicians should be aware of the possibility of late-onset irAEs in patients on receiving long-term ICI treatment.