An 81-year-old woman was admitted to our hospital because of an abnormal opacity on the chest radiograph. She was diagnosed with cT3N3M1a, Stage ⅣA left lower lung lobe adenocarcinoma, and the PD-L1(22C3)expression was high (tumor proportion score[TPS]: 100%). She was administered with pembrolizumab monotherapy because her performance status(PS)was PS 1. After 4 courses, she had a partial response(PR), but her treatment had to be discontinued because of cutaneous adverse effects. After 6 months, the tumor regrew, and atezolizumab monotherapy was provided. Another cutaneous adverse event occurred, and treatment was discontinued again. However, a complete response(CR)was maintained for approximately 2 years and 6 months after discontinuation of treatments.