Nivolumab plus ipilimumab combined therapy is among the most effective therapies for advanced melanoma. However, this therapy is also associated with a high frequency of immune-related adverse events (irAEs). To avoid such severe irAEs caused by additional administration of anti-CTLA4 antibodies, biomarkers to distinguish responders from non-responders among patients treated with anti-PD1 antibodies are important. The purpose of this study is to evaluate the increased serum levels of CCL11, CCL24, and CCL26 as a predictive biomarker for the efficacy of anti-PD1 antibodies in advanced cutaneous melanoma patients. This study analyzed increased serum levels of CCL11, CCL24, and CCL26 in 46 cases of advanced cutaneous melanoma treated with anti-PD1 antibodies. Serum levels on day 42 were compared to baseline (day 0) and analyzed statistically. Receiver operating characteristic curves were established to evaluate the correlation between serum levels of CCL11, CCL24, and CCL26 and efficacy of anti-PD1 antibodies. Increased serum levels of CCL26 correlated significantly with the efficacy of anti-PD1 antibodies. In contrast, no significant correlations were seen between increased serum levels of CCL11 and CCL24 and efficacy of anti-PD1 antibodies. Increased serum levels of CCL26 may be a useful biomarker for identifying those patients with advanced cutaneous melanoma most likely to benefit from anti-melanoma immunotherapy.