Since nivolumab significantly prolongs survival in patients with metastatic melanoma, the number of patients administered nivolumab is increasing, but only 30–40% of patients who received nivolumab monotherapy experienced objective tumor regression. Therefore, enhancing its anti-tumor immune response is of great interest to dermato-oncologists. In this report, we present a case of multiple metastatic melanomas in the lung successfully treated with nivolumab (2 mg/kg every 3 weeks for 12 weeks) followed by ipilimumab (3 mg/kg every 3 weeks for 9 weeks), but with severe liver dysfunction.