A 72-year-old woman with advanced lung cancer had received systemic chemotherapy including atezolizumab. About three months after the initial administration of atezolizumab, her liver enzyme levels increased. The histopathological findings of the initial liver biopsy revealed acute inflammatory infiltrate, predominantly CD3 + , CD4 + and CD8 + T lymphocytes, in the hepatic lobules. We diagnosed her with atezolizumab-induced immune-related acute hepatitis. Oral corticosteroid therapy successfully improved the elevation of serum aminotransferases. A sequential liver biopsy demonstrated the rapid progression of liver fibrosis. Because hepatocellular carcinoma occurs most often in advanced cases of chronic liver disease, we should pay close attention to immune-related acute hepatic injury when treating patients with advanced liver diseases using atezolizumab.